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Aerosol Electroanalysis by PILSNER: Particle-into-Liquid Sampling for Nanoliter Electrochemical Reactions

  • Philip J. Kauffmann
    Philip J. Kauffmann
    Department of Chemistry, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States
    More by Philip J. Kauffmann
  • , 
  • Nathaneal A. Park
    Nathaneal A. Park
    Department of Chemistry, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States
    More by Nathaneal A. Park
  • , 
  • Rebecca B. Clark
    Rebecca B. Clark
    Department of Chemistry, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States
    More by Rebecca B. Clark
    Orcidhttps://orcid.org/0000-0002-0323-2523
  • , 
  • Gary L. Glish
    Gary L. Glish
    Department of Chemistry, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States
    More by Gary L. Glish
    Orcidhttps://orcid.org/0000-0003-2418-4126
  • , and 
  • Jeffrey E. Dick*
    Jeffrey E. Dick
    Department of Chemistry, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States
    Lineberger Comprehensive Cancer Center, School of Medicine, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States
    *Email: [email protected]
    More by Jeffrey E. Dick
    Orcidhttps://orcid.org/0000-0002-4538-9705
Cite this: ACS Meas. Sci. Au 2022, 2, 2, 106–112
Publication Date (Web):November 15, 2021
https://doi.org/10.1021/acsmeasuresciau.1c00024

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Abstract

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Particle-into-liquid sampling (PILS) has enabled robust quantification of analytes of interest in aerosol particles. In PILS, the limit of detection is limited by the factor of particle dilution into the liquid sampling volume. Thus, much lower limits of detection can be achieved by decreasing the sampling volume and increasing the surface area-to-volume ratio of the collection substrate. Unfortunately, few analytical techniques can realize this miniaturization. Here, we use an ultramicroelectrode in a microliter or smaller sampling volume to detect redox active species in aerosols to develop the technique of Particle-into-Liquid Sampling for Nanoliter Electrochemical Reactions (PILSNER). As a proof-of-concept to validate this technique, we demonstrate the detection of K4Fe(CN)6 in aerosol particles (diameter ∼0.1–2 μm) and quantify the electrochemical response. To further explore the utility of the method to detect environmentally relevant redox molecules, we show PILSNER can detect 1 ng/m3 airborne Pb in aerosols. We also demonstrate the feasibility of detecting perfluorooctanesulfonate (PFOS), a persistent environmental contaminant, using this technique. PILSNER is shown to represent a significant advancement toward simple and effective detection of a variety of emerging contaminants with an easily miniaturizable and tunable electroanalytical platform.

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Introduction

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Aerosols, defined as suspensions of liquid or solid particles in a gas, (1) are ubiquitous in almost every environment. Aerosol chemistry and physics are accepted to play critical roles in important natural processes such as cloud formation, (2) ozone depletion, (3) and long-distance chemical transport. (4) Additionally, chronic exposure to high concentrations of aerosols of diameters less than 2.5 μm, often referred to as PM 2.5 in the literature, is linked to numerous health issues including respiratory and heart problems (5) and overall morbidity. Liquid aerosols and microdroplets have also been shown to have unique properties such as reaction rate acceleration (6,7) and spontaneous radical generation, (8) making them of particular analytical interest and relevance. As such, techniques for sampling and analyzing aerosols quickly and accurately are of great importance. While some sampling technology has been developed to meet this need, (9−11) the small size, high physical and chemical heterogeneity, and potential reactivity of aerosols continues to make accurate, inexpensive, and technically simple sampling very challenging. (12)
One commonly employed aerosol sampling technique is particle-into-liquid sampling (PILS). In this technique, particles are impacted onto a liquid interface and incorporated into the bulk solution (or sampling volume). Analytes in the aerosol are extracted by this sampling volume, and the resulting sample is analyzed by another technique, such as mass spectrometry (13) or fluorescence. (14) Despite its analytical power, PILS is limited by both the relatively large volume into which particles are usually sampled (usually on the order of mL, creating a large dilution factor for analytes) as well as its off-line nature. If techniques are developed to probe smaller sampling volumes, the limit of detection (LOD) of PILS can be driven down by orders of magnitude. To mitigate dilution limitations in PILS, we introduce here particle-into-liquid sampling for nanoliter electrochemical reactions (PILSNER).
In PILSNER, a small (200 nL to 20 μL) droplet of water or electrolyte solution serves as a “collector droplet” into which aerosol particles are deposited. In the current work, the aerosol is generated from analyte solutions using a jet nebulizer, but in principle, this technique would work with other natural or artificial aerosol sources. Particles are directed into striking the collector droplet, which itself is in contact with a conductive glassy carbon chip as well as the tip of an ultramicroelectrode (i.e., a scanning electrochemical microscopy (SECM) tip). By using the glassy carbon chip as a counter and pseudoreference electrode, electrochemical techniques can be applied to the droplet to analyze its contents and the contents of the collected aerosol. This strategy for analyzing aerosols is thus both fast and has the potential for very low limits of detection given the inherent capabilities of electrochemical detection and the reduced degree of analyte dilution in small sampling volumes. Figure 1A,B serves to illustrate the experimental setup and the resulting electrochemical responses. In this work, the efficacy of the technique in analyzing the well-behaved redox analyte K4Fe(CN)6 in aerosol is shown using amperometry to track particle collection in real time. Cyclic voltammetry of the collected ferrocyanide was also performed to demonstrate that the system behaves as expected electrochemically (Figure S1). The potential applicability of the technique is demonstrated with the detection of aerosols containing low-ng/m3 concentrations of Pb using anodic stripping voltammetry. The detection of aerosols generated from water solutions of perfluorooctanesulfonate (PFOS), a highly persistent environmental contaminant in rivers and soils, (15) using a molecularly imprinted polymer (MIP)-modified ultramicroelectrode is also shown. The efficacy of this type of MIP-modified ultramicroelectrode has been previously demonstrated, (16−19) and its effectiveness in conjunction with PILSNER demonstrates the potential for the combination of PILSNER with other electrochemical techniques. Broadly speaking, these data demonstrate the potential effectiveness of PILSNER in detecting emerging contaminants in environmental aerosols.

Figure 1

Figure 1. (A) Illustration of the PILSNER setup during the analysis of Pb aerosol via anodic stripping voltammetry and PFOS aerosol via differential pulse voltammetry. (B) Schematic of the PILSNER system. For PFOS analysis, the pseudoreference/counter electrode was modified with a well, as described below.

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Materials and Methods

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Chemicals and Materials

Potassium hexacyanoferrate (II) trihydrate (≥99.95% trace metals basis), ferrocenemethanol (97%), o-phenylenediamine (o-PD, ≥98.0%), and heptadecafluorooctanesulfonic acid potassium salt (PFOS, ≥98.0%) were purchased from Sigma-Aldrich. Lead(II) nitrate (99+%) was purchased from Acros Organics. Potassium chloride (≥99.0%, heavy metals ≤5 ppm) was purchased from Thermo Fisher Scientific. The acetate buffer was made from acetic acid (Sigma-Aldrich, ≥99.95% trace metals basis) and sodium acetate from MCB Reagents (ACS grade). Dulbecco’s phosphate buffered saline (PBS, 1×) was obtained from Gibco. The platinum scanning electrochemical microscopy tip (10 μm diameter, R/G ∼ 25) and the gold scanning electrochemical microscopy tip (12.5 μm diameter) were obtained from CH Instruments (Austin, Texas). All voltammetry and amperometry was performed on the CHI model 601D or 6012D potentiostat. The glassy carbon pseudoreference/counter electrode was obtained from Alfa Aesar. Solutions and water droplets were prepared with ultrapure water (Millipore Milli-Q, 18.2 MΩ·cm). Aerosols were generated by flowing in-house air through a Hudson RCI 1724 nebulizer filled with solution. The flow rate was regulated by an Amvex Medical Flowmeter to 5 L/min. Electrochemical measurements were taken within a well-grounded Faraday cage. Images and videos were captured using a Park Systems CoolingTech Digital Microscope focused and positioned ∼2.5 cm from the electrodes.

Detection of Ferrocyanide

For the detection of ferrocyanide in aerosols, a 0.2–10 μL nano- or microdroplet of ultrapure water was placed onto the glassy carbon chip using a micropipette. The ultramicroelectrode was inserted into the collector droplet via a micropositioner (Model ROE-200, Sutter Instruments) approaching from above the droplet. The ultramicroelectrode tip was positioned approximately in the center of the droplet. Initial contact with the droplet could be observed by the deformation of the droplet into a semiconical shape about the ultramicroelectrode tip. The tip of the nebulizer was positioned ∼1.6 cm away from the droplet. An amperometric i–t curve was used to monitor the spraying and collection of aerosol particles. The measurement was started before spraying, continued while the aerosol was sprayed into the droplet, and ended a short time after the aerosol spraying was stopped. The amperometric i–t curve was performed at +0.6 V versus the glassy carbon pseudoreference electrode with a sample interval of 0.1 s and no quiet time. The voltage used was based on a cyclic voltammogram of a 10 μL potassium hexacyanoferrate droplet obtained with the same setup. Due to the communication between the electrodes and the unique setup of PILSNER, offset currents were baseline subtracted. It should be noted that only amperometry experiments involving ferrocyanide detection were exposed to aerosol and gas flow during the measurement. All other following experiments (anodic stripping, CVs, and DPVs) were performed with no gas flow or aerosol exposure during the electrochemical measurement. We also note that the use of the carbon quasi-reference electrode may induce drift. We generally observed up to 100 mV of drift from experiment to experiment. However, because we are interested most in current magnitude, we used the potential window of the droplet (water oxidation and water/oxygen reduction) to gauge variations in reference electrode between experiments.

Detection of Lead

Anodic stripping voltammetry (ASV) was used to detect Pb in aerosols. Similar to before, a 2 μL droplet of ultrapure water was placed onto the carbon chip. After inserting the ultramicroelectrode into the droplet and adjusting the nebulizer, the solution (100 μM – 10 mM) of Pb(NO3)2 was sprayed at the droplet from a distance of 1.6 cm. The Pb aerosol was sprayed for 60 s before starting the voltammetry. The following settings were used for ASV: a preconcentration time of 240 s, a potential range from −2.0 to 2.0 V, a scan rate of 200 mV/s, and a sample interval of 1 mV.

Fabrication of the MIP-Modified Ultramicroelectrode

The MIP-modified ultramicroelectrode was prepared on a CHI Au SECM tip (r = 6.25 μm) via cyclic voltammetry in a 2:1 (v/v) acetate buffer (pH = 5.8):methanol solution containing 1 mM PFOS and 10 mM o-PD. A glassy carbon rod and Ag/AgCl electrode (stored in 1 M KCl) were used as the counter and reference, respectively. The cyclic voltammetry was performed with a scan rate of 0.2 V/s and potential window of 0 to 1 V vs Ag/AgCl for 10 cycles. Following polymerization, the MIP-modified ultramicroelectrode was incubated in a 50:50 water:methanol solution for 20 min, under mild stirring, in order to extract the template molecules. The ultramicroelectrode was then rinsed with Millipore Milli-Q 18.2 MΩ·cm water before being placed in the sample solution.

Differential Pulse Voltammetry for PFOS Detection

To investigate the performance of the MIP-modified ultramicroelectrode for use in the PILSNER system, control calibration curves monitoring the ultramicroelectrode’s response to increasing concentrations of PFOS via differential pulse voltammetry (DPV) were first constructed in droplets. The MIP-modified Au ultramicroelectrode was used as the working electrode and a glassy carbon chip was used as both the counter and the pseudoreference electrode as described previously. Prior to obtaining each differential pulse voltammogram, the MIP-modified ultramicroelectrode was incubated in a 20 μL droplet of 1× PBS containing 2 mM ferrocene methanol and an appropriate concentration of PFOS for 3 min. The peak height (nA) was recorded from each differential pulse voltammogram, and the blank-subtracted current response (i – io) was used as the response vs increasing concentrations of PFOS. The following parameters were used to perform the differential pulse voltammetry experiments (all potentials are vs the glassy carbon quasi reference electrode): an initial potential of −0.2 V, final potential of 0.5 V, increment of 0.001 V, amplitude of 0.02 V, pulse width of 0.025 s, sample width of 0.0125 s, and pulse period of 0.075 s.
The PILSNER setup itself was slightly modified for the detection of PFOS aerosols. A small section of a pipet tip was cut off and hot-glued to the carbon pseudoreference electrode to produce a small well (diameter of ∼0.5 cm) into which the sample droplet could be placed. This well reduced the evaporation rate of the droplet. It also helped keep the droplet shape by preventing it from spreading across the glassy carbon chip surface, as spraying PFOS into the droplet significantly reduces its surface tension. The collector droplet was a 20 μL droplet of 2 mM ferrocenemethanol in phosphate-buffered saline (PBS). One millimolar PFOS in PBS was then aerosolized into the well at a distance of ∼1.6 cm for 1 or 2 min periods. A DPV measurement was taken after an incubation time of 3 min.

Aerosol Particle Sizing

Aerosol particle sizes were measured with a VPC3000 Counter (Extech Measurement Solutions). The nebulizer tip was positioned perpendicular to the counter inlet and sprayed with 400 mM ferrocyanide for 1 min in cumulative measurement mode. All particle size measurements were repeated in triplicate.

Results and Discussion

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Ferrocyanide Detection and Voltammetry

To understand the underlying physical and chemical mechanisms of PILSNER, aerosol produced by a jet nebulizer from 400 mM ferrocyanide in water was analyzed using a sampling volume of ultrapure water. Amperometric i–t curves of experiments repeated with different collector droplet sizes are shown in Figure 2. A clear increase in current magnitude corresponding to the collection and subsequent oxidation of analyte is observed in each experiment. As the sampling volume gets larger, the magnitude of the current change also gets larger. The decrease in current magnitude after the jet nebulizer is turned off at 60 s is likely due to decreased convection in the sampling volume, lowering the limiting current value. The limiting current (ilim) on an ultramicroelectrode is directly related to the concentration of redox active species by ilim = 4nFDCa, where n is the stoichiometric number of electrons, F is Faraday’s constant (96 485 C·mol–1), D is the diffusion coefficient of redox species (∼7 × 10–10 m2·s–1), C is the concentration (the value we calculate from this analysis), and a is the radius of the ultramicroelectrode (5 μm). For reference, the calculated concentrations of ferrocyanide in the collector droplet for the 0.2, 0.5, and 2 μL collector droplet traces were 6.1, 17.6, and 24.7 mM, respectively. It should be noted that these concentrations are not the same as the concentration in the sample aerosol; the difficulty in determining the “true” analyte concentration in the aerosol is discussed below. Cyclic voltammograms of the sampling volume in the absence of impacting aerosol particles containing captured ferrocyanide were used to further validate the collection of aerosol particles (Figure S1). The distance between the ultramicroelectrode and the reference/counter electrode is on the order of a millimeter. Considering the Einstein diffusion equation (Eqn. S2), the amount of time it would take species to diffuse between electrodes is ∼100 s. Thus, we expect no feedback effect (20) in our analyses. This will become a consideration for much smaller droplets.

Figure 2

Figure 2. PILSNER i–t curves of various sample volumes exposed to 400 mM ferrocyanide aerosol. The sample volume was exposed to aerosol from t = 30 s to t = 60 s. Baseline adjusted.

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The magnitude of the drop in limiting current in the amperometry experiments was used to estimate, based on average aerosol particle size and concentration measurements (Figure S2), that approximately 107 particles were collected during each of the 30 s experiment windows (Eqn. S1). Because liquid aerosols rapidly evaporate under most conditions due to their high surface area, (21) which concentrates their contents, this estimate represents an upper bound. It is likely that the number of aerosols captured is much smaller, as the original count estimate assumes that there is no particle evaporation and the final ferrocyanide concentration in the aerosol is still 400 mM (where it likely is higher). This is further corroborated by the fact that the number of aerosol particles collected, calculated in Eqn. S1 from the electrochemical data, seemingly exceeds the total particle count measured by the Extech counter. This places the theoretical electrochemical upper limit of detection for captured particles, based on the volume of delivered aerosol, at roughly 103 particles/mL concentrations. It is worth noting, however, that only a fraction of the total particles are captured, and a measurement of the exact collection efficiency of particles cannot be determined without a more accurate and technically demanding determination of aerosol particle sizes post-evaporation (as a function of distance from the collector volume, time, and aerosol composition). Improving this collection efficiency with improved geometry and aerosol introduction would reduce the LOD further. Reducing the size of the collector also improves the LOD by reducing the factor by which captured particles are diluted, in accordance with Equation S1. The size of the sampling volume is perhaps the most critical parameter influencing performance in PILSNER. As has been presented, a predominantly water-containing collector droplet evaporates slowly over time. This evaporation rate is dependent on the humidity, which is a limitation that will be studied and mitigated in future work using ionic liquids as the collector droplet material. The effect of collector droplet evaporation for a 2 μL droplet is included in Figure S6. For the sampling of natural aerosols, the velocity of ambient aerosol particles will also likely be of concern during collection. For such sampling, we propose the use of a pump to accelerate particles toward the collector droplet at similar volumetric rates to what is used in this work (5 L/min). There is significant precedent for using pumps for the purpose of aerosol sampling up to high flow rates (>20 L/min). (22,23)
The experiments in Figure 2 do not show an increase in current magnitude with decreasing collector droplet size despite the reduction in particle dilution. This observation may be due to mechanical differences in aerosol collection not directly related to the volume of the collector droplet; specifically, it is possible that the higher curvature of smaller droplets is less conducive to aerosol collection. The effect of convection is also evident in observations regarding the speed of signal onset during PILSNER. Collector droplet size affects the maximum time required for complete diffusional mixing of aerosol analytes in the collector. For a 1 μL droplet, the time for signal onset caused purely by diffusion is calculated to be about 1 min using the Einstein relation (Eqn. S2). However, video recordings of aerosol collection (Figure S3) in PILSNER indicate that mixing is nearly immediate, with current increases occurring within <1 s of aerosol introduction. This further suggests that convective mixing caused by the aerosol and gas impacting the collector droplet is the dominant mechanism of droplet homogenization while the nebulizer is turned on. The effect of convective mixing within the collector droplet, as well as the effect of reducing droplet sizes to even smaller nanoliter volumes, will be the subject of future study.

Lead Detection via Anodic Stripping Voltammetry

The analysis of Pb in aerosol was also performed to demonstrate the applicability of PILSNER for the detection of environmentally relevant contaminants. Aerosolized particles containing Pb are an EPA-monitored health concern, generated largely by industrial processes such as mining or smelting, or as combustion byproducts. (24)Figure 3 shows an anodic stripping voltammogram of two experiments using aerosol generated from 100 μM lead(II) nitrate and water. The oxidation peak around −1 V represents the stripping of Pb deposited on the ultramicroelectrode. Figure S4 shows the anodic stripping voltammograms of several experiments using aerosol generated from either water or lead(II) nitrate. These experiments demonstrate that the LOD of PILSNER for detecting aerosolized Pb is at least 100 μM (2 ppm in the aerosol). This concentration corresponds to a total airborne Pb concentration of 1 ng/m3 of aerosol-containing gas based on the flow rate of supply gas and estimated particle counts (Eqn. S3). For comparison, exposure to Pb aerosol may be as high as tens to hundreds of μg/m3 in high-exposure workplaces such as manufacturing sites, (25) and the EPA three-month average exposure limit for suspended airborne Pb is 150 ng/m3. (26) This LOD suggests PILSNER may be well suited for analyzing Pb aerosol exposure. This LOD represents a lower bound, as the concentration calculation assumes that no evaporation of the aerosol has occurred prior to size measurement. However, even given a hypothetical situation where 99% of the water in the aerosol has evaporated, the estimate of the PILSNER Pb LOD would still be around 100 ng/m3, which is still appropriately sensitive for sampling natural aerosols. These LODs compare favorably with typical LODs and background species detection limits for traditional bulk PILS, which vary with the target aerosol but have been reported to be in the roughly 50–200 ng/m3 range. (27,28) We hypothesize this LOD may still be improved by aforementioned optimization steps. For example, the LOD of PILSNER is dependent in part on the LOD of the anodic stripping voltammetry being applied, which itself is based in large part on the preconcentration time applied to the collector. Preconcentration time in PILSNER is then in turn limited by the evaporation rate of the collector, the mitigation of which will be a separate avenue of future experimentation. Electrode fouling, especially for ultramicroelectrode, may also occur in lead and gasoline-containing aerosols with high organic content. The extent and mitigation of this effect would warrant further investigation for the application of PILSNER to this particular type of measurement.

Figure 3

Figure 3. PILSNER-anodic stripping voltammogram of water and lead(II) nitrate aerosols. Listed concentrations indicate concentrations in the aerosol particles. Baseline adjusted.

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PFOS Detection via Differential Pulse Voltammetry

The use of DPV to detect PFOS in PBS buffer was performed to demonstrate the potential of hybridizing PILSNER with other established electrochemical techniques in order to expand its applicability. The performance of the MIP-modified ultramicroelectrodes in collector droplets containing known concentrations of PFOS (sans aerosol exposure) is demonstrated in Figure 4, showing high linearity (R2 > 0.90). This expected voltammetric behavior with respect to the decreasing current response observed with increasing PFOS concentrations occurs as a result of PFOS molecules occluding the molecularly imprinted cavities on the surface of the modified ultramicroelectrode. A slight shift in the voltage corresponding to each peak current in each trace toward more positive voltages was observed with increasing PFOS concentrations. This effect is not exclusive to MIPs used with PILNSER and is discussed by Glasscott et al. (19) This shift is hypothesized to be the result of mass or charge transfer effects arising from the interaction of analyte with the surface structure of the modified ultramicroelectrode.

Figure 4

Figure 4. (A) DPV response in 20 μL droplets of 1× PBS with 2 mM ferrocene methanol and increasing concentrations of PFOS using a MIP-modified Au ultramicroelectrode, and the same glassy carbon chip quasi-reference electrode and counter used throughout this work. All DPVs were normalized such that the starting current was 0 nA. (B) The resulting calibration curve from the DPVs in panel A, illustrating the dependence of the blank subtracted current response (i – io), on the natural log of PFOS concentration, with the x-axis on a logarithmic scale. The equation of best fit was y = 0.06(±0.01) ln(x) + 0.50(±0.04) and the R2 value was 0.93 (±0.04). All points were statistically different according to a one-way ANOVA test (n = 3). The LOD of PFOS detection in the collector droplet was determined to be 0.3 pM based on the sensitivity of the calibration curve and an assessment of that slope against 3 times the noise of the blank (0 nM) peak current measurement.

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To demonstrate the compatibility of PILSNER with the MIP-modified ultramicroelectrode, Figure 5 shows data from DPV measurements taken on a PBS droplet exposed to 1 mM PFOS aerosol for an increasing duration. Similar to the control MIP ultramicroelectrode experiment, a progressive decrease in voltammetric response is observed as the concentration of PFOS in the droplet increases over the duration of the aerosol exposure. This hybrid technique thus has the potential for real-time quantification of PFOS in natural aerosol particles. Considering that most persistent PFOS contamination is found in water sources such as streams and rivers given that it is a legacy compound, (29) PILSNER-DPV may also represent an alternative technique by which such samples may be analyzed with little to no sample preparation other than the need for nebulization.

Figure 5

Figure 5. DPV responses in a 20 μL droplet of 1× PBS with 2 mM ferrocene methanol exposed to 1 mM PFOS aerosol for 1, 2, 3, and 5 min compared to a precollection pulse. All DPVs were normalized such that the starting current was 0 nA.

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Conclusion

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The ability of a new technique, particle-into-liquid sampling for nanoliter electrochemical reactions (PILSNER) to detect liquid aerosol containing electrochemically active species has been demonstrated. Analysis of ferrocyanide aerosol using amperometry has shown that this technique effectively captures particles, and once deposited, analytes in the PILSNER collector can be analyzed electrochemically. The analysis of Pb aerosol using anodic stripping voltammetry and of PFOS aerosol by differential pulse voltammetry also shows that this technique has the potential for sensitive detection of heavy metal contaminants and other pollutants. Our results indicate PILSNER is an effective means by which ultramicroelectrodes can be used for ultrasensitive aerosol electroanalysis.

Supporting Information

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The Supporting Information is available free of charge at https://pubs.acs.org/doi/10.1021/acsmeasuresciau.1c00024.

  • Video of PILSNER collection (ZIP)

  • Calculations of aerosol counts, diffusion times, and aerosol volumes; ferrocyanide cyclic voltammograms; aerosol histograms; overlaid anodic stripping voltammograms; images of collector droplet; humidity-based amperometric response curve; statistical analyses; PFOS DPV initial currents; non-normalized PFOS DPV response; and amperometric controls (PDF)

Terms & Conditions

Most electronic Supporting Information files are available without a subscription to ACS Web Editions. Such files may be downloaded by article for research use (if there is a public use license linked to the relevant article, that license may permit other uses). Permission may be obtained from ACS for other uses through requests via the RightsLink permission system: http://pubs.acs.org/page/copyright/permissions.html.

Author Information

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  • Corresponding Author
    • Jeffrey E. Dick - Department of Chemistry, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States;  Lineberger Comprehensive Cancer Center, School of Medicine, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States;  Orcidhttps://orcid.org/0000-0002-4538-9705;  Email: [email protected]
  • Authors
    • Philip J. Kauffmann - Department of Chemistry, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States
    • Nathaneal A. Park - Department of Chemistry, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States
    • Rebecca B. Clark - Department of Chemistry, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States;  Orcidhttps://orcid.org/0000-0002-0323-2523
    • Gary L. Glish - Department of Chemistry, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States;  Orcidhttps://orcid.org/0000-0003-2418-4126
  • Author Contributions

    P.J.K. and N.A.P. contributed equally to this work.

  • Funding

    This work was completed with financial support from the Chemical Measurement and Imaging Program in the National Science Foundation Division of Chemistry under Grant CHE-2003587.

  • Notes
    The authors declare no competing financial interest.

Acknowledgments

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JED acknowledges Matthew W. Glasscott and Lee C. Moores for insightful discussions.

Abbreviations

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PILS

particle-into-liquid sampling

PILSNER

particle-into-liquid sampling for nanoliter electrochemical reactions

PFOS

perfluorooctanesulfonate

CV

cyclic voltammogram

MIP

molecularly imprinted polymer

SECM

scanning electrochemical microscopy

DPV

differential pulse voltammetry

ASV

anodic stripping voltammetry

References

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This article references 29 other publications.

  1. 1
    Kaiser, J. Mounting Evidence Indicates Fine-Particle Pollution. Science 2005, 307 (5717), 1858– 1861,  DOI: 10.1126/science.307.5717.1858b
    [Crossref], [CAS], Google Scholar
    1
    How dirt air hurts the heart
    Kaiser, Jocelyn
    Science (Washington, DC, United States) (2005), 307 (5717), 1858-1859CODEN: SCIEAS; ISSN:0036-8075. (American Association for the Advancement of Science)
    There is no expanded citation for this reference.
    >> More from SciFinder ®
    https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD2MXislCitrw%253D&md5=1cfd9c354d3f17f8ed43cdaa84df8cd9
  2. 2
    Vignati, E.; Raes, F.; Van Dingenen, R.; Putaud, J.; Herzog, M.; Penner, J. E.; Walton, J. J.; Kreidenweis, S. M.; Harrington, D. Y. Modelling and Observations of Aerosol Properties in the Clean and Polluted Marine Boundary Layer and Free Troposphere Modeling of Global Sulfate Aerosol Number Concentrations. 15th International Conference on Nucleation and Atmospheric Aerosols 2000, 677– 681,  DOI: 10.1063/1.1361956
    [Crossref], Google Scholar
    There is no corresponding record for this reference.
  3. 3
    Molina, M. J.; Rowland, F. S. Stratospheric Sink of Chlorofluoromethanes: Chlorine Atom-Catalyzed Destruction of Ozone. Nature 1974, 249 (6), 810,  DOI: 10.1038/249810a0
    [Crossref], [CAS], Google Scholar
    3
    Stratospheric sink for chlorofluoromethanes. Chlorine atom-catalyzed destruction of ozone
    Molina, Mario J.; Rowland, F. S.
    Nature (London, United Kingdom) (1974), 249 (5460), 810-12CODEN: NATUAS; ISSN:0028-0836.
    Photolytic dissocn. of atm. CFCl3 and CF2Cl2 gives Cl which destroys the O3 layer. The halomethanes may remain at altitudes of 20-40 km for 40-150 yr and will reach satn. values of 10-30 times the present levels.
    >> More from SciFinder ®
    https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADyaE2cXlslGntr8%253D&md5=22b7d89924fe7c1d85c85896b3bf3e7e
  4. 4
    Kim, Y. J.; Woo, J. H.; Ma, Y., II; Kim, S.; Nam, J. S.; Sung, H.; Choi, K. C.; Seo, J.; Kim, J. S.; Kang, C. H. Chemical Characteristics of Long-Range Transport Aerosol at Background Sites in Korea. Atmos. Environ. 2009, 43 (34), 5556– 5566,  DOI: 10.1016/j.atmosenv.2009.03.062
    [Crossref], [CAS], Google Scholar
    4
    Chemical characteristics of long-range transport aerosol at background sites in Korea
    Kim, Yoo-Jung; Woo, Jung-Hun; Ma, Young-Il; Kim, Suhyang; Nam, Jung-Sik; Sung, Hakyoung; Choi, Ki-Chul; Seo, Jihyun; Kim, Jeong-Su; Kang, Chang-Hee; Lee, Gangwoong; Ro, Chul-Un; Chang, Duk; Sunwoo, Young
    Atmospheric Environment (2009), 43 (34), 5556-5566CODEN: AENVEQ; ISSN:1352-2310. (Elsevier Ltd.)
    In this study, background concn. sites of Deokjeok and Gosan, which were deemed suitable for monitoring the impact of long-range transported air pollutants, were selected. An investigation of the source types of pollutants, their locations, and relative quant. contributions to the particulate concns. at both sites using appropriate methodologies to make initial estns. was conducted. Episodic measurements of PM2.5, PM10, and size distribution, along with its ion and carbon components were performed from 2005 to 2007, and a comprehensive anal. of the results was conducted utilizing back trajectory anal. As for frequency of wind direction, it was quite apparent that the two sites are heavily influenced by air masses originating from the eastern and northern regions of China. For PM2.5 and PM10, the mass concns. from north and east China were higher than other cases, originating from the ocean. In the northerly-wind case, meteorol. properties for Deokjeok and Gosan and the influence of carbon emissions from northwest Korea resulted in a changing of air mass properties during transport. As was the case with mass concn., the highest contribution for ionic and carbon components of PM2.5 and PM10 for both sites appeared for the westerly wind case. A specially high relative contribution, greater than 1.4 times, was apparent in the secondary aerosol case because of a large influence of long-range transported pollutants from east China. Carbon components exhibited different behaviors for the northerly and westerly wind cases compared with secondary aerosol. The major reason for this discrepancy appears to be the carbon emissions from northwest Korea.
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  5. 5
    Kennedy, I. M. The Health Effects of Combustion-Generated Aerosols. Proc. Combust. Inst. 2007, 31 (II), 2757– 2770,  DOI: 10.1016/j.proci.2006.08.116
    [Crossref], [CAS], Google Scholar
    5
    The health effects of combustion-generated aerosols
    Kennedy, Ian M.
    Proceedings of the Combustion Institute (2007), 31 (Pt. 2), 2757-2770CODEN: PCIRC2; ISSN:1540-7489. (Elsevier)
    A review. The link between exposure to fine particles in the atm. and adverse health effects has been well-established by epidemiol. studies. Most of the fine and ultrafine material of concern derives from combustion sources and is largely a mixt. of elemental and org. carbon, metals, and inorg. compds. such as sulfates. When inhaled by people, the particles can be taken-up by cells in the lung. The particles can also penetrate into the circulatory system and lodge in organs such as the liver and heart. The mechanism for their impact on health is not entirely understood although the generation of reactive oxygen species such as the OH radical is a major focus. The inflammation that can be caused by these reactive species can exacerbate pre-existing ailments. Combustion conditions in mobile and stationary sources can affect the reactivity of aerosols and their ability to generate reactive oxygen species. Combustion conditions can also affect the speciation of transition metals, the morphol. of particles and their compn., and their size, all parameters that may lead to adverse health effects.
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  6. 6
    Marsh, B. M.; Iyer, K.; Cooks, R. G. Reaction Acceleration in Electrospray Droplets: Size, Distance, and Surfactant Effects. J. Am. Soc. Mass Spectrom. 2019, 30, 2022– 2030,  DOI: 10.1007/s13361-019-02264-w
    [ACS Full Text ACS Full Text], [CAS], Google Scholar
    6
    Reaction Acceleration in Electrospray Droplets: Size, Distance, and Surfactant Effects
    Marsh, Brett M.; Iyer, Kiran; Cooks, R. Graham
    Journal of the American Society for Mass Spectrometry (2019), 30 (10), 2022-2030CODEN: JAMSEF; ISSN:1044-0305. (Springer)
    Phenylhydrazone formation from isatin is used to examine the effects on the reaction rate of (i) electrospray emitter distance from the mass spectrometer (MS) inlet, (ii) emitter tip diam., and (iii) presence of surfactant. Reaction rates are characterized through measurement of conversion ratios. It is found that there is an increase in the conversion ratio as (i) the electrospray source is moved further from the inlet of the mass spectrometer, (ii) smaller sprayer diams. are used, and (iii) when surfactants are present. Each of these exptl. operations is assocd. with an increase in reaction rate and with a decrease in av. droplet sizes. The size measurements are made using super resoln. microscopy from the "splash" on a collector surface produced by a fluorescent marker sprayed using conditions similar to those used for the reaction mixt. This measurement showed that droplets undergo significant evapn. as a function of distance of flight, thereby increasing their surface to vol. ratios. Similarly, the effect of nanoelectrospray emitter size on conversion ratio is also found to be assocd. with changes in droplet size for which a 4 to 10 times increase in reaction rate is seen using tip diams. ranging from 20 μm down to 1 μm. Finally, the effects of surfactants in producing smaller droplets with corresponding large increases in reaction rate are demonstrated by splash microscopy. These findings point to reaction acceleration being strongly assocd. with reactions at the surfaces of microdroplets. [Figure not available: see fulltext.].
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  7. 7
    Sahota, N.; Abusalim, D. I.; Wang, M. L.; Brown, C. J.; Zhang, Z.; El-Baba, T. J.; Cook, S. P.; Clemmer, D. E. A Microdroplet-Accelerated Biginelli Reaction: Mechanisms and Separation of Isomers Using IMS-MS. Chem. Sci. 2019, 10, 4822,  DOI: 10.1039/C9SC00704K
    [Crossref], [PubMed], [CAS], Google Scholar
    7
    A microdroplet-accelerated Biginelli reaction: mechanisms and separation of isomers using IMS-MS
    Sahota, Navneet; AbuSalim, Deyaa I.; Wang, Melinda L.; Brown, Christopher J.; Zhang, Zhicaho; El-Baba, Tarick J.; Cook, Silas P.; Clemmer, David E.
    Chemical Science (2019), 10 (18), 4822-4827CODEN: CSHCCN; ISSN:2041-6520. (Royal Society of Chemistry)
    Electrospray ionization (ESI) combined with ion mobility spectrometry (IMS) and mass spectrometry (MS) techniques is used to examine the Biginelli reaction in an ensemble of ions generated from droplets. We find evidence for rapid dihydropyrimidinone formation from condensation of Et acetoacetate, benzaldehyde, and urea on the very short timescales assocd. with the electrospray process (∼10 μs to ∼1.0 ms). Control bulk-soln. reactions show no product formation even after several days. This implies that the in-droplet reaction rate is enhanced by an astonishing factor. Examn. of the reaction conditions and characterization of the intermediates en route to product shows evidence for variations in the reaction mechanism. IMS sepn. shows that the Knoevenagel condensation intermediate from benzaldehyde and Et acetoacetate exists as both the cis- and trans-isomer, in a ∼5 to 1 ratio. We suggest that the dramatic acceleration arises because of increased reagent confinement as electrosprayed droplets shrink. The ability of IMS-MS to resolve intermediates (including isomers) provides a new means of understanding reaction pathways.
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  8. 8
    Lee, J. K.; Walker, K. L.; Han, H. S.; Kang, J.; Prinz, F. B.; Waymouth, R. M.; Nam, H. G.; Zare, R. N. Spontaneous Generation of Hydrogen Peroxide from Aqueous Microdroplets. Proc. Natl. Acad. Sci. U. S. A. 2019, 116 (39), 19294– 19298,  DOI: 10.1073/pnas.1911883116
    [Crossref], [PubMed], [CAS], Google Scholar
    8
    Spontaneous generation of hydrogen peroxide from aqueous microdroplets
    Lee, Jae Kyoo; Walker, Katherine L.; Han, Hyun Soo; Kang, Jooyoun; Prinz, Fritz B.; Waymouth, Robert M.; Nam, Hong Gil; Zare, Richard N.
    Proceedings of the National Academy of Sciences of the United States of America (2019), 116 (39), 19294-19298CODEN: PNASA6; ISSN:0027-8424. (National Academy of Sciences)
    We show H2O2 is spontaneously produced from pure water by atomizing bulk water into microdroplets (1μm to 20μm in diam.). Prodn. of H2O2, as assayed by H2O2-sensitive fluorescence dye peroxyfluor-1, increased with decreasing microdroplet size. Cleavage of 4-carboxyphenylboronic acid and conversion of phenylboronic acid to phenols in microdroplets further confirmed the generation of H2O2. The generated H2O2 concn. was ≈30μM (≈1 part per million) as detd. by titrn. with potassium titanium oxalate. Changing the spray gas to O2 or bubbling O2 decreased the yield of H2O2 in microdroplets, indicating that pure water microdroplets directly generate H2O2 without help from O2 either in air surrounding the droplet or dissolved in water. We consider various possible mechanisms for H2O2 formation and report a no. of different expts. exploring this issue. We suggest that hydroxyl radical (OH) recombination is the most likely source, in which OH is generated by loss of an electron from OH- at or near the surface of the water microdroplet. This catalyst-free and voltage-free H2O2 prodn. method provides innovative opportunities for green prodn. of hydrogen peroxide.
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  9. 9
    Spencer, S. E.; Tyler, C. A.; Tolocka, M. P.; Glish, G. L. Low-Temperature Plasma Ionization-Mass Spectrometry for the Analysis of Compounds in Organic Aerosol Particles. Anal. Chem. 2015, 87 (4), 2249– 2254,  DOI: 10.1021/ac5038889
    [ACS Full Text ACS Full Text], [CAS], Google Scholar
    9
    Low-Temperature Plasma Ionization-Mass Spectrometry for the Analysis of Compounds in Organic Aerosol Particles
    Spencer, Sandra E.; Tyler, Chelsea A.; Tolocka, Michael P.; Glish, Gary L.
    Analytical Chemistry (Washington, DC, United States) (2015), 87 (4), 2249-2254CODEN: ANCHAM; ISSN:0003-2700. (American Chemical Society)
    Low-temp. plasma ionization, a technique that causes minimal fragmentation during ionization, is investigated as an ionization technique for mass spectrometric detection of the compds. in ambient org. aerosols in real time. The expts. presented in this paper demonstrate that ions are generated from compds. in the aerosol particles. The utility of this technique for detection of both pos. and neg. ions from the pyrolyzate of multiple natural polymers (Et cellulose, cellulose, and lignin) is presented. Ultimately, low-temp. plasma ionization is shown to be a promising ionization technique for detection of compds. in org. aerosols by mass spectrometry.
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  10. 10
    Swanson, K. D.; Worth, A. L.; Glish, G. L. Use of an Open Port Sampling Interface Coupled to Electrospray Ionization for the On-Line Analysis of Organic Aerosol Particles. J. Am. Soc. Mass Spectrom. 2018, 29 (2), 297– 303,  DOI: 10.1007/s13361-017-1776-y
    [ACS Full Text ACS Full Text], [CAS], Google Scholar
    10
    Use of an Open Port Sampling Interface Coupled to Electrospray Ionization for the On-Line Analysis of Organic Aerosol Particles
    Swanson, Kenneth D.; Worth, Anne L.; Glish, Gary L.
    Journal of the American Society for Mass Spectrometry (2018), 29 (2), 297-303CODEN: JAMSEF; ISSN:1044-0305. (Springer)
    A simple design for an open port sampling interface coupled to electrospray ionization (OPSI-ESI) is presented for the anal. of org. aerosols. The design uses minimal modifications to a Bruker electrospray (ESI) emitter to create a continuous flow, self-aspirating open port sampling interface. Considerations are presented for introducing aerosol to the open port sampling interface including aerosol gas flow and solvent flow rates. The device was demonstrated for use with an aerosol of nicotine as well as aerosol formed in the pyrolysis of biomass. Upon comparison with extractive electrospray ionization (EESI), this device has similar sensitivity with increased reproducibility by nearly a factor of three. The device has the form factor of a std. Bruker/Agilent ESI emitter and can be used without any further instrument modifications. [Figure not available: see fulltext.].
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  11. 11
    Canagaratna, M. R.; Jayne, J. T.; Jimenez, J. L.; Allan, J. D.; Alfarra, M. R.; Zhang, Q.; Onasch, T. B.; Drewnick, F.; Coe, H.; Middlebrook, A. Chemical and Microphysical Characterization of Ambient Aerosols with the Aerodyne Aerosol Mass Spectrometer. Mass Spectrom. Rev. 2007, 26 (2), 185– 222,  DOI: 10.1002/mas.20115
    [Crossref], [PubMed], [CAS], Google Scholar
    11
    Chemical and microphysical characterization of ambient aerosols with the aerodyne aerosol mass spectrometer
    Canagaratna, M. R.; Jayne, J. T.; Jimenez, J. L.; Allan, J. D.; Alfarra, M. R.; Zhang, Q.; Onasch, T. B.; Drewnick, F.; Coe, H.; Middlebrook, A.; Delia, A.; Williams, L. R.; Trimborn, A. M.; Northway, M. J.; DeCarlo, P. F.; Kolb, C. E.; Davidovits, P.; Worsnop, D. R.
    Mass Spectrometry Reviews (2007), 26 (2), 185-222CODEN: MSRVD3; ISSN:0277-7037. (John Wiley & Sons, Inc.)
    A review. The application of mass spectrometric techniques to the real-time measurement and characterization of aerosols represents a significant advance in the field of atm. science. This review focuses on the aerosol mass spectrometer (AMS), an instrument designed and developed at Aerodyne Research, Inc. (ARI) that is the most widely used thermal vaporization AMS. The AMS uses aerodynamic lens inlet technol. together with thermal vaporization and electron-impact mass spectrometry to measure the real-time non-refractory (NR) chem. speciation and mass loading as a function of particle size of fine aerosol particles with aerodynamic diams. between ∼50 and 1,000 nm. The original AMS utilizes a quadrupole mass spectrometer (Q) with electron impact (EI) ionization and produces ensemble av. data of particle properties. Later versions employ time-of-flight (ToF) mass spectrometers and can produce full mass spectral data for single particles. This manuscript presents a detailed discussion of the strengths and limitations of the AMS measurement approach and reviews how the measurements are used to characterize particle properties. Results from selected lab. expts. and field measurement campaigns are also presented to highlight the different applications of this instrument. Recent instrumental developments, such as the incorporation of softer ionization techniques (vacuum UV (VUV) photo-ionization, Li+ ion, and electron attachment) and high-resoln. ToF mass spectrometers, that yield more detailed information about the org. aerosol component are also described.
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  12. 12
    McMurry, P. A Review of Atmospheric Aerosol Measurements. Atmos. Environ. 2000, 34 (12–14), 1959– 1999,  DOI: 10.1016/S1352-2310(99)00455-0
    [Crossref], [CAS], Google Scholar
    12
    A review of atmospheric aerosol measurements
    McMurry, Peter H.
    Atmospheric Environment (2000), 34 (12-14), 1959-1999CODEN: AENVEQ; ISSN:1352-2310. (Elsevier Science Ltd.)
    Recent developments in atm. aerosol measurements are reviewed with many refs. The topics included complement those covered in the recent review by Chow which focuses on regulatory compliance measurements and filter measurements of particulate compn. This review focuses on measurements of aerosol integral properties (total no. concn., CCN concn., optical coeffs., etc.), aerosol phys. chem. properties (d., refractive index, equil. water content, etc.), measurements of aerosol size distributions, and measurements of size-resolved aerosol compn. Such measurements play an essential role in studies of secondary aerosol formation by atm. chem. transformations and enable one to quantify the contributions of various species to effects including light scattering/absorption, health effects, dry deposition, etc. Aerosol measurement evolved from an art to a science in the 1970s following the development of instrumentation to generate monodisperse calibration aerosols of known size, compn., and concn. While such calibration tools permit precise assessments of instrument responses to known lab.-generated aerosols, unquantifiable uncertainties remain even when carefully calibrated instruments are used for atm. measurements. This is because instrument responses typically depend on aerosol properties including compn., shape, d., etc., which, for atm. aerosols, may vary from particle-to-particle and are often unknown. More effort needs to be made to quantify measurement accuracies that can be achieved for realistic atm. sampling scenarios. The measurement of org. species in atm. particles requires substantial development. Atm. aerosols typically include hundreds of org. compds., and only a small fraction (∼ 10%) of these can be identified by state-of-the-art anal. methodologies. Even the measurement of the total particulate org. carbon mass concn. is beset by difficulties including the unknown extent of evaporative losses during sampling, adsorption of gas-phase org. compds. onto sampling substrates, and the unknown relationship between carbon mass and mass of the particulate orgs. The development of improved methodologies for such measurements should be a high priority for the future. Mass spectrometers that measure the compn. of individual particles have recently been developed. It is not clear that these instruments will provide quant. information on species mass concns., and more work is needed to routinely interpret the vast quantities of data generated during field sampling. Nevertheless, these instruments substantially expand the range of atm. aerosol issues that can be explored exptl. These instruments represent the most significant advance in aerosol instrumentation in recent years.
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  13. 13
    Bateman, A. P.; Nizkorodov, S. A.; Laskin, J.; Laskin, A. High-Resolution Electrospray Ionization Mass Spectrometry Analysis of Water-Soluble Organic Aerosols Collected with a Particle into Liquid Sampler. Anal. Chem. 2010, 82 (19), 8010– 8016,  DOI: 10.1021/ac1014386
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    13
    High-Resolution Electro-spray Ionization Mass Spectrometry Analysis of Water-Soluble Organic Aerosols Collected with a Particle into Liquid Sampler
    Bateman, Adam P.; Nizkorodov, Sergey A.; Laskin, Julia; Laskin, Alexander
    Analytical Chemistry (Washington, DC, United States) (2010), 82 (19), 8010-8016CODEN: ANCHAM; ISSN:0003-2700. (American Chemical Society)
    This work demonstrated the utility of a particle-into-liq. sampler (PILS), a technique traditionally used to identify inorg. ions present in ambient or lab. aerosols, for anal. of water-sol. org. aerosol (OA) by high-resoln. electro-spray ionization mass spectrometry (HR-ESI-MS). Secondary org. aerosol (SOA) was produced from 0.5 ppm mixing ratios of limonene and O3 in a 5 m3 Teflon chamber. SOA was simultaneously collected using a traditional filter sampler and a PILS. Filter samples were extd. with water or acetonitrile; the aq. PILS samples were directly analyzed. In terms of peak abundance, types of detectable compds., av. O:C ratio, and org. mass:org. C ratio, the resulting high-resoln. mass spectra were essentially identical for PILS- and filter-based samples. SOA compds. extd. from filter/acetonitrile extn. and PILS/water extn. accounted for >95% of the total ion current in ESI mass spectra. This similarity was attributed to high soly. of limonene SOA in water. Significant differences in detected ions and peak abundance were obsd. for pine needle biomass burning org. aerosol (BBOA) collected with PILS and filter sampling. The BBOA water-sol. fraction was considerably smaller than for SOA, and several unique peaks were detectable only with the filter/acetonitrile method. The combination of PILS collection with HR-ESI-MS anal. offers a new approach for mol. anal. of the water-sol. org. fraction in biogenic SOA, aged photochem. smog, and BBOA.
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  14. 14
    Tang, H.; Hiemstra, S.; Thompson, J. E. Characterization of a Novel Particle into Liquid Sampler for Analysis of Single Fluorescent Aerosol Particles through Capillary Electrophoresis. Anal. Chim. Acta 2011, 702 (1), 120– 126,  DOI: 10.1016/j.aca.2011.06.029
    [Crossref], [PubMed], [CAS], Google Scholar
    14
    Characterization of a novel particle into liquid sampler for analysis of single fluorescent aerosol particles through capillary electrophoresis
    Tang, Hao; Hiemstra, Scott; Thompson, Jonathan E.
    Analytica Chimica Acta (2011), 702 (1), 120-126CODEN: ACACAM; ISSN:0003-2670. (Elsevier B.V.)
    An approach to sample and analyze single aerosolized droplets (<10 nL) of solns. contg. fluorescein isothiocyanate (FITC)-labeled glycine (GLY) and glutamic acid (GLU) was demonstrated. This sampling approach is based on inertial impaction in which the sample particle is accelerated through a nozzle and directly into a small drop of buffered soln. (20 mM borate, pH = 10) suspended at the end of a coaxial stainless steel tube with a fused SiO2 capillary. A spherical light scattering cell and laser (λ = 532 nm) detects the particle arrival at the buffered droplet. Upon dissoln. and/or mixing, a portion of the sample is injected onto the fused SiO2 capillary for subsequent chem. anal. by capillary electrophoresis (CE) with laser-induced fluorescence detection. The inertial impaction approach sampled particles >1 μm diam. with an efficiency ≥80%. At 15 kV applied potential, the FITC GLY and GLU conjugates could be resolved in <120 s, allowing qual. anal. of the contents of single dispersed particles; however, the extent to which the sample is dild. in the buffer droplet varied significantly on a per-particle basis, causing a >80% relative std. deviation in fluorescence peak heights. This aspect of the method necessitates using internal stds. to quant. analyze materials present within the particles. It is envisaged that further improvements to the described device may ultimately lead to anal. of the contents of single particles dispersed in the earth atm.
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  15. 15
    Wang, Z.; DeWitt, J. C.; Higgins, C. P.; Cousins, I. T. A Never-Ending Story of Per- and Polyfluoroalkyl Substances (PFASs)?. Environ. Sci. Technol. 2017, 51, 2508– 2518,  DOI: 10.1021/acs.est.6b04806
    [ACS Full Text ACS Full Text], [CAS], Google Scholar
    15
    A Never-Ending Story of Per- and Polyfluoroalkyl Substances (PFASs)?
    Wang, Zhanyun; DeWitt, Jamie C.; Higgins, Christopher P.; Cousins, Ian T.
    Environmental Science & Technology (2017), 51 (5), 2508-2518CODEN: ESTHAG; ISSN:0013-936X. (American Chemical Society)
    A review. More than 3000 per- and polyfluoroalkyl substances (PFASs) are, or have been, on the global market, yet most research and regulation continues to focus on a limited selection of rather well-known long-chain PFASs, particularly perfluorooctanesulfonate (PFOS), perfluorooctanoic acid (PFOA) and their precursors. Continuing to overlook the vast majority of other PFASs is a major concern for society. We provide recommendations for how to proceed with research and cooperation to tackle the vast no. of PFASs on the market and in the environment.
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  16. 16
    Kazemi, R.; Potts, E. I.; Dick, J. E. Quantifying Interferent Effects on Molecularly Imprinted Polymer Sensors for Per- And Polyfluoroalkyl Substances (PFAS). Anal. Chem. 2020, 92 (15), 10597– 10605,  DOI: 10.1021/acs.analchem.0c01565
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    16
    Quantifying interferent effects on molecularly imprinted polymer sensors for per- and polyfluoroalkyl substances (PFAS)
    Kazemi, Rezvan; Potts, Emili I.; Dick, Jeffrey E.
    Analytical Chemistry (Washington, DC, United States) (2020), 92 (15), 10597-10605CODEN: ANCHAM; ISSN:0003-2700. (American Chemical Society)
    Per- and polyfluoroalkyl substances (PFAS) are emerging as harmful environmental micropollutants. Generally, PFAS species are quantified by mass spectrometry, for which a collected sample is taken to a centralized facility. Robust techniques to quantify PFAS in the field are necessary to diagnose environmental contamination at the earliest onset of pollution. Here, we developed a molecularly imprinted polymer (MIP) electrode for the detection of perfluorooctanesulfonate (PFOS) and explored the MIP surface and the effects of interfering mols. MIPs were formed by the anodic deposition of o-phenylenediamine (o-PD) in the presence of PFOS template mols. on a glassy carbon macroelectrode. The performance of the resulting MIP electrode was evaluated by the current obtained from the oxidn. of ferrocene carboxylic acid as the electrochem. probe. The MIP electrode was able to detect PFOS with a detection limit of 0.05 nM, which is lower than the health advisory limit of 0.14 nM reported by the U.S. EPA. To better understand PFOS assocn. into the MIP, a Langmuir binding model was developed based on the changes in electrochem. responses of the MIP. Fitting the model to the exptl. data gave an assocn. const. (KA) of 4.95 x 1012 over a PFOS concn. range of 0 to 0.05 nM. The binding isotherm of other commonly found substances in contaminated water sources such as chloride, humic acid, perfluorooctanoic acid (PFOA), and perfluorobutanesulfonate (PFBS) was also investigated. In the case of chloride and humic acid, the calcd. KA values of 9.05 x 107 and 6.01 x 105, resp., indicate relatively weak adsorption of these species on the MIP. However, PFOA, which is the carboxylate analog of PFOS, revealed a very close KA value (3.41 x 1012) to PFOS. A greater KA value (1.43 x 1013) was obtained for PFBS, which possesses the same functional group and a smaller mol. size compared to PFOS. The presented platform emphasizes the necessity to develop new strategies to make MIP sensors more specific if practical applications are to be pursued.
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  17. 17
    Karimian, N.; Stortini, A. M.; Moretto, L. M.; Costantino, C.; Bogialli, S.; Ugo, P. Electrochemosensor for Trace Analysis of Perfluorooctanesulfonate in Water Based on a Molecularly Imprinted Poly(o-Phenylenediamine) Polymer. ACS Sensors 2018, 3 (7), 1291– 1298,  DOI: 10.1021/acssensors.8b00154
    [ACS Full Text ACS Full Text], [CAS], Google Scholar
    17
    Electrochemosensor for Trace Analysis of Perfluorooctanesulfonate in Water Based on a Molecularly Imprinted Poly(o-phenylenediamine) Polymer
    Karimian, Najmeh; Stortini, Angela M.; Moretto, Ligia M.; Costantino, Claudio; Bogialli, Sara; Ugo, Paolo
    ACS Sensors (2018), 3 (7), 1291-1298CODEN: ASCEFJ; ISSN:2379-3694. (American Chemical Society)
    This work is aimed at developing an electrochem. sensor for the sensitive and selective detection of trace levels of perfluorooctanesulfonate (PFOS) in water. Contamination of waters by perfluorinated alkyl substances (PFAS) is a problem of global concern due to their suspected toxicity and ability to bioaccumulate. PFOS is the perfluorinated compd. of major concern, as it has the lowest suggested control concns. The sensor reported here is based on a gold electrode modified with a thin coating of a molecularly imprinted polymer (MIP), prepd. by anodic electropolymn. of o-phenylenediamine (o-PD) in the presence of PFOS as the template. Activation of the sensor is achieved by template removal with suitable a solvent mixt. Voltammetry, a quartz crystal microbalance, SEM and elemental anal. were used to monitor the electropolymn. process, template removal, and binding of the analyte. Ferrocenecarboxylic acid (FcCOOH) has been exploited as an electrochem. probe able to generate anal. useful voltammetric signals by competing for the binding sites with PFOS, as the latter is not electroactive. The sensor has a low detection limit (0.04 nM), a satisfactory selectivity, and is reproducible and repeatable, giving anal. results in good agreement with those obtained by HPLC-MS/MS analyses.
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  18. 18
    Clark, R. B.; Dick, J. E. Electrochemical Sensing of Perfluorooctanesulfonate (PFOS) Using Ambient Oxygen in River Water. ACS Sensors 2020, 5 (11), 3591– 3598,  DOI: 10.1021/acssensors.0c01894
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    18
    Electrochemical sensing of perfluorooctanesulfonate (PFOS) using ambient oxygen in river water
    Clark, Rebecca B.; Dick, Jeffrey E.
    ACS Sensors (2020), 5 (11), 3591-3598CODEN: ASCEFJ; ISSN:2379-3694. (American Chemical Society)
    Per- and polyfluoroalkyl substances (PFAS) are an emerging class of pervasive and harmful micropollutant. Next-generation sensors are necessary to detect PFAS at sub-nanomolar levels. Electrochem. can measure analyte concns. at sub-10 nM levels and offers a deployable platform; however, the lack of chem. reactivity of PFAS species requires electrode surface functionalization with a molecularly imprinted polymer (MIP). Previously, such sensors have required a well-characterized one-electron mediator (i.e., ferrocene carboxylic acid or ferrocene methanol) for detection. Natural waterways do not have an abundance of ferrocenyl compds. for quantification, implying that these mediators limit sensor practicality, deployability, and cost. Here, we take advantage of ambient oxygen present in river water to quantify one of the more harmful PFAS mols., perfluorooctanesulfonate (PFOS), from 0 to 0.5 nM on a MIP-modified carbon substrate. Differential pulse voltammetry (DPV) and electrochem. impedance spectroscopy (EIS) generated calibration curves for PFOS in river water using oxygen as the mediator. Importantly, we show that electrochem. impedance spectroscopy is superior to voltammetric techniques: like ultramicroelectrodes, this technique can be used in low-cond. matrixes like river water with high reproducibility. Further, impedance provides a PFOS limit of detection of 3.4 pM. We also demonstrate that the common interferents humic acid and chloride do not affect the sensor signal. These results are a necessary step forward in developing deployable sensors that act as a first line of defense for detecting PFAS contamination at its earliest onset.
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  19. 19
    Glasscott, M. W.; Vannoy, K. J.; Kazemi, R.; Verber, M. D.; Dick, J. E. μ-MIP: Molecularly Imprinted Polymer-Modified Microelectrodes for the Ultrasensitive Quantification of GenX (HFPO-DA) in River Water. Environ. Sci. Technol. Lett. 2020, 7 (7), 489– 495,  DOI: 10.1021/acs.estlett.0c00341
    [ACS Full Text ACS Full Text], [CAS], Google Scholar
    19
    μ-MIP: Molecularly Imprinted Polymer-Modified Microelectrodes for the Ultrasensitive Quantification of GenX (HFPO-DA) in River Water
    Glasscott, Matthew W.; Vannoy, Kathryn J.; Kazemi, Rezvan; Verber, Matthew D.; Dick, Jeffrey E.
    Environmental Science & Technology Letters (2020), 7 (7), 489-495CODEN: ESTLCU; ISSN:2328-8930. (American Chemical Society)
    Per- and polyfluoroalkyl substances (PFAS) are emerging as a hazardous class of environmental micropollutant, and robust, sensitive, and inexpensive sensing modalities are needed to detect the earliest onset of contamination of surface water. Here, the authors present a molecularly imprinted polymer (MIP)-modified microelectrode (r = 6.25 μm) sensor for the quantification of a pervasive environmental PFAS, GenX (HFPO-DA), in surface water obtained from the Haw River in North Carolina. A 20 nm film of o-phenylenediamine was electropolymd. in the presence of GenX to generate a templated polymer adjacent to the electrode surface with subsequent solvent extn. resulting in GenX-specific recognition sites. The oxidn. of ferrocene methanol was obsd. as a function of GenX concn., and the current decreased linearly with the concn. of GenX. A linear dynamic range of 1-5000 pM with a limit of detection of 250 fM and excellent selectivity against environmental interferents, such as humic acid and perfluorooctanesulfonate, was achieved. The use of oxygen redn. as an addnl. ambient detection mechanism and the amenability of microelectrodes to relatively resistive environmental matrixes extend the applicability of MIP-modified microelectrodes to environmental waterways as deployable sensors.
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  20. 20
    Kwak, J.; Bard, A. J. Scanning Electrochemical Microscopy. Theory of the Feedback Mode. Anal. Chem. 1989, 61 (11), 1221– 1227,  DOI: 10.1021/ac00186a009
    [ACS Full Text ACS Full Text], [CAS], Google Scholar
    20
    Scanning electrochemical microscopy. Theory of the feedback mode
    Kwak, Juhyoun; Bard, Allen J.
    Analytical Chemistry (1989), 61 (11), 1221-7CODEN: ANCHAM; ISSN:0003-2700.
    The steady-state current that flows between the scanning tip (a disk ultramicroelectrode imbedded in an insulating sheath) and a planar sample substrate in a scanning electrochem. microscope (SECM) operating in the feedback mode was calcd. by the finite element method with an exponentially expanding grid, for both conductive and insulating samples. For conductive substrates the tip current, representing, for example, the oxidn. reaction of R to O, is enhanced by flow of R generated at the substrate to the tip and is a function of tip/substrate distance, d, but not the radius of the insulating sheath. For insulating substrates, the tip current is decreased by blockage of the diffusion of R to the tip by the substrate and depends upon d and the insulating sheath radius. The theor. results were compared to exptl. studies.
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  21. 21
    Wright, T. P.; Song, C.; Sears, S.; Petters, M. D. Thermodynamic and Kinetic Behavior of Glycerol Aerosol. Aerosol Sci. Technol. 2016, 50 (12), 1385– 1396,  DOI: 10.1080/02786826.2016.1245405
    [Crossref], [CAS], Google Scholar
    21
    Thermodynamic and kinetic behavior of glycerol aerosol
    Wright, Timothy P.; Song, Chen; Sears, Stephen; Petters, Markus D.
    Aerosol Science and Technology (2016), 50 (12), 1385-1396CODEN: ASTYDQ; ISSN:0278-6826. (Taylor & Francis, Inc.)
    Glycerol and propylene glycol mixts. are common carrier solns. in electronic cigarettes. Aerosols produced from these mixts. will evap. quickly in a dry environment due to their high volatility. In a humid environment, such as the lungs, the kinetics of evapn. and hygroscopic growth det. the evolution of aerosol plume glycerol. Here, we apply a temp. and relative humidity-controlled hygroscopicity/volatility tandem differential mobility analyzer system to study the growth and evapn. kinetics of glycerol aerosol over a wide range of temp., relative humidity, and residence times. Results show that at dry conditions glycerol aerosols evap. within seconds at temps. warmer than 20°C and that the accommodation coeff. of glycerol vapor on dry glycerol particles is 0.8. Under humidified conditions, the mutual depression of vapor pressures of the aq. glycerol/water soln. slows the glycerol evapn. rate consistent with thermodn. and kinetic model predictions. Model calcns. show that water vapor aided condensation of glycerol can occur at high relative humidity for glycerol vapor concns. that result in glycerol particle evapn. under dry conditions. The combined results will help with constraining computational modules that model the evolution of glycerol-contg. aerosols along a prescribed thermodn. trajectory. Copyright 2016 American Assocn. for Aerosol Research.
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  22. 22
    Demokritou, P.; Kavouras, I. G.; Ferguson, S. T.; Koutrakis, P. Development of a High Volume Cascade Impactor for Toxicological and Chemical Characterization Studies. Aerosol Sci. Technol. 2002, 36 (9), 925– 933,  DOI: 10.1080/02786820290092113
    [Crossref], [CAS], Google Scholar
    22
    Development of a high volume cascade impactor for toxicological and chemical characterization studies
    Demokritou, P.; Kavouras, I. G.; Ferguson, S. T.; Koutrakis, P.
    Aerosol Science and Technology (2002), 36 (9), 925-933CODEN: ASTYDQ; ISSN:0278-6826. (Taylor & Francis Inc.)
    This paper presents the design and development of a compact high-vol. cascade impactor (HVCI). The HVCI operates at a flow rate of 900 L/min and consists of 4 impaction stages equipped with circular slit-shaped acceleration nozzles and a backup filter. The backup filter is placed downstream of the fourth stage and is used to collect the ultrafine particles (particle size <0.1 μm). The major feature of this novel sampler is its ability to collect relatively large amts. of particles (milligram-gram levels) onto relatively small polyurethane foam substrates without using adhesives. As previously reported, the capacity of the impaction substrate is 2.15 g of collected particles per cm2 of foam. Although the impaction substrates are not coated with adhesives such as grease or mineral oil, particle bounce and re-entrainment losses were found not to be significant. Particles can be easily recovered from the foam substrates using aq. extn. The impactor was calibrated using polydisperse particles. The 50% cutpoints of the 4 stages were 9.90, 2.46, 1.0, and 0.1 μm, resp. Interstage losses of ultrafine and fine particles were <10% and for coarse particles were <20%. The pressure drop across the 4 stages and the backup filter were 0.25, 0.75, 1.25, 19.9, and 3.3 kPa, resp.
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  23. 23
    John, W.; Reischl, G. A Cyclone for Size-Selective Sampling of Ambient Air. J. Air Pollut. Control Assoc. 1980, 30 (8), 872– 876,  DOI: 10.1080/00022470.1980.10465122
    [Crossref], [CAS], Google Scholar
    23
    A cyclone for size-selective sampling of ambient air
    John, Walter; Reischl, Georg
    Journal of the Air Pollution Control Association (1980), 30 (8), 872-6CODEN: JPCAAC; ISSN:0002-2470.
    A cyclone with a 47 mm after-filter has been developed for ambient air size-selective monitoring. It has been extensively evaluated with lab.-generated aerosol. Variation of the pressure drop and 50% cut point with flow rate show that th cyclone operates in a single flow regime with a vortex in the outlet flow. The particle size cutoff curve is comparable in sharpness to a cascade impactor and is the same for solid or liq. particles. At 21.7 L/min, the 50% particle diam. cutoff (D50) is 2.5 and at 15.4 L/min, D50 is 3.5 μm. Collection efficiency data for flow of 8-27 L/min fit a universal curve when plotted vs. the normalized particle diam., (D-D50)/D50. Reentrainment of previously deposited particles is <1% of the loading/day.
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  24. 24
    Salcedo, D.; Onasch, T. B.; Aiken, A. C.; Williams, L. R.; De Foy, B.; Cubison, M. J.; Worsnop, D. R.; Molina, L. T.; Jimenez, J. L. Determination of Particulate Lead Using Aerosol Mass Spectrometry: MILAGRO/MCMA-2006 Observations. Atmos. Chem. Phys. 2010, 10 (12), 5371– 5389,  DOI: 10.5194/acp-10-5371-2010
    [Crossref], Google Scholar
    There is no corresponding record for this reference.
  25. 25
    Tsai, C. J.; Shih, T. S.; Sheu, R. N. Characteristics of Lead Aerosols in Different Work Environments. Am. Ind. Hyg. Assoc. J. 1997, 58 (9), 650– 656,  DOI: 10.1080/15428119791012441
    [Crossref], [PubMed], [CAS], Google Scholar
    25
    Characteristics of lead aerosols in different work environments
    Tsai, Chuen-Jinn; Shih, Tung-Sheng; Sheu, Rong-Nan
    American Industrial Hygiene Association Journal (1997), 58 (9), 650-656CODEN: AIHAAP; ISSN:0002-8894. (American Industrial Hygiene Association)
    Air samples were collected to examine phys. and chem. characteristics of Pb aerosols in different work environments in the airborne Pb concn. of 28-783 μg/m3. Size distribution of aerosols was measured using a Marple personal cascade impactor, and Pb anal. was conducted using graphite at. absorption spectrometry. Pb aerosol size distribution was different from that of total particles. Such differences are not negligible and must be taken into account when estg. aerosol deposition within the human respiratory tract. Variation of MMAD (mass median aerodynamic diam.) and GSD (geometric std. deviation) of Pb aerosols in the coarse mode with total airborne concn. was small, and the assumption that Pb aerosol distribution is const. is reasonable for establishing the relationship between airborne Pb and blood Pb concns. Respirable Pb concn. was well correlated with the total airborne Pb concn. in all work areas of the three plants except the charging area of the capacitor plant. Therefore, it is expected that either total airborne Pb or respirable airborne Pb concn. can be used to correlate blood Pb concn.
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  26. 26
    U. S. EPA Review of the National Ambient Air Quality Standards for Lead 2016, 81, 845,  DOI: 10.1002/9781119117896.ch68
    [Crossref], Google Scholar
    There is no corresponding record for this reference.
  27. 27
    Sorooshian, A.; Brechtel, F. J.; Ma, Y.; Weber, R. J.; Corless, A.; Flagan, R. C.; Seinfeld, J. H. Modeling and Characterization of a Particle-into-Liquid Sampler (PILS). Aerosol Sci. Technol. 2006, 40 (6), 396– 409,  DOI: 10.1080/02786820600632282
    [Crossref], [CAS], Google Scholar
    27
    Modeling and Characterization of a Particle-into-Liquid Sampler (PILS)
    Sorooshian, Armin; Brechtel, Fred; Ma, Yilin; Weber, Rodney; Corless, Andrew; Flagan, Richard; Seinfeld, John
    Aerosol Science and Technology (2006), 40 (6), 396-409CODEN: ASTYDQ; ISSN:0278-6826. (Taylor & Francis, Inc.)
    A modified particle-into-liq. sampler (PILS), based on the original design of R.J. Weber, et al. (2001), is discussed. The principal modification in this design is that collected liq. sample is delivered to vials held on a rotating carousel vs. an online anal. detector. A model was developed to predict aerosol mass concns. measured by a PILS based on sampled aerosol operating parameters and characteristics. A backward model predicted sampled aerosol concns. based on operating parameters and concns. measured by PILS. Both models, which consider plumbing transmission efficiency, droplet growth, mixing effects, and volatilization loss, predicted mass concns. which were consistent with lab. tests for concn. step changes. Av. collection efficiency for species (Na+, K+, SO42-, Cl-, NO3-) from a variety of aerosols vs. simultaneous measurements with a differential mobility analyzer (DMA) exceeded 96% except for NH4+ (88%); NH4+ was theor. shown to be the most vulnerable to volatilization, followed by Cl- and NO3-, with greater losses caused by increasing droplet pH and temp. Characterization tests highlighted the importance of reducing NH4+ volatilization by keeping a stable tip temp. of 100° at the point where steam and ambient air mix in the condensation chamber. Maintaining a stable tip temp. also avoided fluctuations in super-saturations which led to increased deposition losses of larger droplets. Sample data from the 2004 International Consortium for Atm. Research on Transport and Transformation field campaign are presented.
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  28. 28
    Fukami, C. S.; Sullivan, A. P.; Ryan Fulgham, S.; Murschell, T.; Borch, T.; Smith, J. N.; Farmer, D. K. Technical Note: An Improved Approach to Determining Background Aerosol Concentrations with PILS Sampling on Aircraft. Atmos. Environ. 2016, 136, 16– 20,  DOI: 10.1016/j.atmosenv.2016.04.005
    [Crossref], [CAS], Google Scholar
    28
    Technical note: An improved approach to determining background aerosol concentrations with PILS sampling on aircraft
    Fukami, Christine S.; Sullivan, Amy P.; Ryan Fulgham, S.; Murschell, Trey; Borch, Thomas; Smith, James N.; Farmer, Delphine K.
    Atmospheric Environment (2016), 136 (), 16-20CODEN: AENVEQ; ISSN:1352-2310. (Elsevier Ltd.)
    Particle-into-Liq. Samplers (PILS) have become a std. aerosol collection technique, and are widely used in both ground and aircraft measurements in conjunction with off-line ion chromatog. (IC) measurements. Accurate and precise background samples are essential to account for gas-phase components not efficiently removed and any interference in the instrument lines, collection vials or off-line anal. procedures. For aircraft sampling with PILS, backgrounds are typically taken with in-line filters to remove particles prior to sample collection once or twice per flight with more numerous backgrounds taken on the ground. Here, we use data collected during the Front Range Air Pollution and Photochem. E´xperiment (FRAPPE´) to demonstrate that not only are multiple background filter samples are essential to attain a representative background, but that the chem. background signals do not follow the Gaussian statistics typically assumed. Instead, the background signals for all chem. components analyzed from 137 background samples (taken from ∼78 total sampling hours over 18 flights) follow a log-normal distribution, meaning that the typical approaches of averaging background samples and/or assuming a Gaussian distribution cause an over-estn. of background samples - and thus an underestimation of sample concns. Our approach of deriving backgrounds from the peak of the log-normal distribution results in detection limits of 0.25, 0.32, 3.9, 0.17, 0.75 and 0.57 μg m-3 for sub-micron aerosol nitrate (NO-3), nitrite (NO-2), ammonium (NH+4), sulfate (SO2-4), potassium (K+) and calcium (Ca2+), resp. The difference in backgrounds calcd. from assuming a Gaussian distribution vs. a log-normal distribution were most extreme for NH+4, resulting in a background that was 1.58× that detd. from fitting a log-normal distribution.
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  29. 29
    Pétré, M.-A.; Koropeckyj-Cox, L.; Duboscq, S. M.; Genereux, D. P.; Knappe, D. R. U.; Gilmore, T. E.; Hopkins, Z. R. Per- and Polyfluoroalkyl Substance (Pfas) Transport From Groundwater To Streams Near a Pfas Manufacturing Facility in North Carolina, Usa. Environ. Sci. Technol. 2021, 55 (9), 5848– 5856,  DOI: 10.1021/acs.est.0c07978
    [ACS Full Text ACS Full Text], [CAS], Google Scholar
    29
    Per- and polyfluoroalkyl substance (PFAS) transport from groundwater to streams near a PFAS manufacturing facility in North Carolina, USA
    Petre, Marie-Amelie; Genereux, David P.; Koropeckyj-Cox, Lydia; Knappe, Detlef R. U.; Duboscq, Sandrine; Gilmore, Troy E.; Hopkins, Zachary R.
    Environmental Science & Technology (2021), 55 (9), 5848-5856CODEN: ESTHAG; ISSN:0013-936X. (American Chemical Society)
    We quantified per- and polyfluoroalkyl substance (PFAS) transport from groundwater to five tributaries of the Cape Fear River near a PFAS manufg. facility in North Carolina (USA). Hydrol. and PFAS data were coupled to quantify PFAS fluxes from groundwater to the tributaries. Up to 29 PFAS were analyzed, including perfluoroalkyl acids and recently identified fluoroethers. Total quantified PFAS (ΣPFAS) in groundwater was 20-4773 ng/L (mean = 1863 ng/L); the range for stream water was 426-3617 ng/L (mean = 1717 ng/L). Eight PFAS constituted 98% of ΣPFAS; perfluoro-2-(perfluoromethoxy)propanoic acid (PMPA) and hexafluoropropylene oxide dimer acid (GenX) accounted for 61%. For PFAS discharge from groundwater to one tributary, values estd. from stream water measurements (18 ± 4 kg/yr) were similar to those from groundwater measurements in streambeds (22-25 ± 5 kg/yr). At baseflow, 32 ± 7 kg/yr of PFAS discharged from groundwater to the five tributaries, eventually reaching the Cape Fear River. Given the PFAS emission timeline at the site, groundwater data suggest the abundant fluoroethers moved through the subsurface to streams in «50 yr. Discharge of contaminated groundwater may lead to long-term contamination of surface water and impacts on downstream drinking water supplies. This work addresses a gap in the PFAS literature: quantifying PFAS mass transfer between groundwater and surface water using field data.
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Cited By

This article is cited by 5 publications.

  1. Philip J. Kauffmann, Nicole L. Walker, Vanshika Gupta, Jeffrey E. Dick. Triple-Barrel Ultramicroelectrodes for Multipurpose, Submilliliter Electroanalysis. Analytical Chemistry 2023, 95 (22) , 8411-8416. https://doi.org/10.1021/acs.analchem.3c00735
  2. Nathaneal A. Park, Gary L. Glish, Jeffrey E. Dick. Investigating Electrosprayed Droplets Using Particle-into-Liquid Sampling for Nanoliter Electrochemical Reactions. Journal of the American Society for Mass Spectrometry 2023, 34 (2) , 320-327. https://doi.org/10.1021/jasms.2c00338
  3. Kathryn J. Vannoy, Nicole E. Tarolla, Philip J. Kauffmann, Rebecca B. Clark, Jeffrey E. Dick. Detecting Methamphetamine in Aerosols by Electroanalysis in a Soap Bubble Wall. Analytical Chemistry 2022, 94 (16) , 6311-6317. https://doi.org/10.1021/acs.analchem.2c00462
  4. Philip Kauffmann, Jeffrey Dick. Evaluating important analytical figures of merit for PILSNER: particle-into-liquid sampling for nanoliter electrochemical reactions. Analytical and Bioanalytical Chemistry 2023, 307 https://doi.org/10.1007/s00216-023-04557-2
  5. Sondrica Goines, Jeffrey E. Dick. Investigating the cytotoxic redox mechanism of PFOS within Hep G2 by hyperspectral-assisted scanning electrochemical microscopy. The Analyst 2022, 147 (19) , 4356-4364. https://doi.org/10.1039/D2AN00904H
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  • Abstract

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    Figure 1

    Figure 1. (A) Illustration of the PILSNER setup during the analysis of Pb aerosol via anodic stripping voltammetry and PFOS aerosol via differential pulse voltammetry. (B) Schematic of the PILSNER system. For PFOS analysis, the pseudoreference/counter electrode was modified with a well, as described below.

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    Figure 2

    Figure 2. PILSNER i–t curves of various sample volumes exposed to 400 mM ferrocyanide aerosol. The sample volume was exposed to aerosol from t = 30 s to t = 60 s. Baseline adjusted.

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    Figure 3

    Figure 3. PILSNER-anodic stripping voltammogram of water and lead(II) nitrate aerosols. Listed concentrations indicate concentrations in the aerosol particles. Baseline adjusted.

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    Figure 4

    Figure 4. (A) DPV response in 20 μL droplets of 1× PBS with 2 mM ferrocene methanol and increasing concentrations of PFOS using a MIP-modified Au ultramicroelectrode, and the same glassy carbon chip quasi-reference electrode and counter used throughout this work. All DPVs were normalized such that the starting current was 0 nA. (B) The resulting calibration curve from the DPVs in panel A, illustrating the dependence of the blank subtracted current response (i – io), on the natural log of PFOS concentration, with the x-axis on a logarithmic scale. The equation of best fit was y = 0.06(±0.01) ln(x) + 0.50(±0.04) and the R2 value was 0.93 (±0.04). All points were statistically different according to a one-way ANOVA test (n = 3). The LOD of PFOS detection in the collector droplet was determined to be 0.3 pM based on the sensitivity of the calibration curve and an assessment of that slope against 3 times the noise of the blank (0 nM) peak current measurement.

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    Figure 5

    Figure 5. DPV responses in a 20 μL droplet of 1× PBS with 2 mM ferrocene methanol exposed to 1 mM PFOS aerosol for 1, 2, 3, and 5 min compared to a precollection pulse. All DPVs were normalized such that the starting current was 0 nA.

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    This article references 29 other publications.

    1. 1
      Kaiser, J. Mounting Evidence Indicates Fine-Particle Pollution. Science 2005, 307 (5717), 1858– 1861,  DOI: 10.1126/science.307.5717.1858b
      [Crossref], [CAS], Google Scholar
      1
      How dirt air hurts the heart
      Kaiser, Jocelyn
      Science (Washington, DC, United States) (2005), 307 (5717), 1858-1859CODEN: SCIEAS; ISSN:0036-8075. (American Association for the Advancement of Science)
      There is no expanded citation for this reference.
      >> More from SciFinder ®
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    2. 2
      Vignati, E.; Raes, F.; Van Dingenen, R.; Putaud, J.; Herzog, M.; Penner, J. E.; Walton, J. J.; Kreidenweis, S. M.; Harrington, D. Y. Modelling and Observations of Aerosol Properties in the Clean and Polluted Marine Boundary Layer and Free Troposphere Modeling of Global Sulfate Aerosol Number Concentrations. 15th International Conference on Nucleation and Atmospheric Aerosols 2000, 677– 681,  DOI: 10.1063/1.1361956
      [Crossref], Google Scholar
      There is no corresponding record for this reference.
    3. 3
      Molina, M. J.; Rowland, F. S. Stratospheric Sink of Chlorofluoromethanes: Chlorine Atom-Catalyzed Destruction of Ozone. Nature 1974, 249 (6), 810,  DOI: 10.1038/249810a0
      [Crossref], [CAS], Google Scholar
      3
      Stratospheric sink for chlorofluoromethanes. Chlorine atom-catalyzed destruction of ozone
      Molina, Mario J.; Rowland, F. S.
      Nature (London, United Kingdom) (1974), 249 (5460), 810-12CODEN: NATUAS; ISSN:0028-0836.
      Photolytic dissocn. of atm. CFCl3 and CF2Cl2 gives Cl which destroys the O3 layer. The halomethanes may remain at altitudes of 20-40 km for 40-150 yr and will reach satn. values of 10-30 times the present levels.
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    4. 4
      Kim, Y. J.; Woo, J. H.; Ma, Y., II; Kim, S.; Nam, J. S.; Sung, H.; Choi, K. C.; Seo, J.; Kim, J. S.; Kang, C. H. Chemical Characteristics of Long-Range Transport Aerosol at Background Sites in Korea. Atmos. Environ. 2009, 43 (34), 5556– 5566,  DOI: 10.1016/j.atmosenv.2009.03.062
      [Crossref], [CAS], Google Scholar
      4
      Chemical characteristics of long-range transport aerosol at background sites in Korea
      Kim, Yoo-Jung; Woo, Jung-Hun; Ma, Young-Il; Kim, Suhyang; Nam, Jung-Sik; Sung, Hakyoung; Choi, Ki-Chul; Seo, Jihyun; Kim, Jeong-Su; Kang, Chang-Hee; Lee, Gangwoong; Ro, Chul-Un; Chang, Duk; Sunwoo, Young
      Atmospheric Environment (2009), 43 (34), 5556-5566CODEN: AENVEQ; ISSN:1352-2310. (Elsevier Ltd.)
      In this study, background concn. sites of Deokjeok and Gosan, which were deemed suitable for monitoring the impact of long-range transported air pollutants, were selected. An investigation of the source types of pollutants, their locations, and relative quant. contributions to the particulate concns. at both sites using appropriate methodologies to make initial estns. was conducted. Episodic measurements of PM2.5, PM10, and size distribution, along with its ion and carbon components were performed from 2005 to 2007, and a comprehensive anal. of the results was conducted utilizing back trajectory anal. As for frequency of wind direction, it was quite apparent that the two sites are heavily influenced by air masses originating from the eastern and northern regions of China. For PM2.5 and PM10, the mass concns. from north and east China were higher than other cases, originating from the ocean. In the northerly-wind case, meteorol. properties for Deokjeok and Gosan and the influence of carbon emissions from northwest Korea resulted in a changing of air mass properties during transport. As was the case with mass concn., the highest contribution for ionic and carbon components of PM2.5 and PM10 for both sites appeared for the westerly wind case. A specially high relative contribution, greater than 1.4 times, was apparent in the secondary aerosol case because of a large influence of long-range transported pollutants from east China. Carbon components exhibited different behaviors for the northerly and westerly wind cases compared with secondary aerosol. The major reason for this discrepancy appears to be the carbon emissions from northwest Korea.
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    5. 5
      Kennedy, I. M. The Health Effects of Combustion-Generated Aerosols. Proc. Combust. Inst. 2007, 31 (II), 2757– 2770,  DOI: 10.1016/j.proci.2006.08.116
      [Crossref], [CAS], Google Scholar
      5
      The health effects of combustion-generated aerosols
      Kennedy, Ian M.
      Proceedings of the Combustion Institute (2007), 31 (Pt. 2), 2757-2770CODEN: PCIRC2; ISSN:1540-7489. (Elsevier)
      A review. The link between exposure to fine particles in the atm. and adverse health effects has been well-established by epidemiol. studies. Most of the fine and ultrafine material of concern derives from combustion sources and is largely a mixt. of elemental and org. carbon, metals, and inorg. compds. such as sulfates. When inhaled by people, the particles can be taken-up by cells in the lung. The particles can also penetrate into the circulatory system and lodge in organs such as the liver and heart. The mechanism for their impact on health is not entirely understood although the generation of reactive oxygen species such as the OH radical is a major focus. The inflammation that can be caused by these reactive species can exacerbate pre-existing ailments. Combustion conditions in mobile and stationary sources can affect the reactivity of aerosols and their ability to generate reactive oxygen species. Combustion conditions can also affect the speciation of transition metals, the morphol. of particles and their compn., and their size, all parameters that may lead to adverse health effects.
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    6. 6
      Marsh, B. M.; Iyer, K.; Cooks, R. G. Reaction Acceleration in Electrospray Droplets: Size, Distance, and Surfactant Effects. J. Am. Soc. Mass Spectrom. 2019, 30, 2022– 2030,  DOI: 10.1007/s13361-019-02264-w
      [ACS Full Text ACS Full Text], [CAS], Google Scholar
      6
      Reaction Acceleration in Electrospray Droplets: Size, Distance, and Surfactant Effects
      Marsh, Brett M.; Iyer, Kiran; Cooks, R. Graham
      Journal of the American Society for Mass Spectrometry (2019), 30 (10), 2022-2030CODEN: JAMSEF; ISSN:1044-0305. (Springer)
      Phenylhydrazone formation from isatin is used to examine the effects on the reaction rate of (i) electrospray emitter distance from the mass spectrometer (MS) inlet, (ii) emitter tip diam., and (iii) presence of surfactant. Reaction rates are characterized through measurement of conversion ratios. It is found that there is an increase in the conversion ratio as (i) the electrospray source is moved further from the inlet of the mass spectrometer, (ii) smaller sprayer diams. are used, and (iii) when surfactants are present. Each of these exptl. operations is assocd. with an increase in reaction rate and with a decrease in av. droplet sizes. The size measurements are made using super resoln. microscopy from the "splash" on a collector surface produced by a fluorescent marker sprayed using conditions similar to those used for the reaction mixt. This measurement showed that droplets undergo significant evapn. as a function of distance of flight, thereby increasing their surface to vol. ratios. Similarly, the effect of nanoelectrospray emitter size on conversion ratio is also found to be assocd. with changes in droplet size for which a 4 to 10 times increase in reaction rate is seen using tip diams. ranging from 20 μm down to 1 μm. Finally, the effects of surfactants in producing smaller droplets with corresponding large increases in reaction rate are demonstrated by splash microscopy. These findings point to reaction acceleration being strongly assocd. with reactions at the surfaces of microdroplets. [Figure not available: see fulltext.].
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    7. 7
      Sahota, N.; Abusalim, D. I.; Wang, M. L.; Brown, C. J.; Zhang, Z.; El-Baba, T. J.; Cook, S. P.; Clemmer, D. E. A Microdroplet-Accelerated Biginelli Reaction: Mechanisms and Separation of Isomers Using IMS-MS. Chem. Sci. 2019, 10, 4822,  DOI: 10.1039/C9SC00704K
      [Crossref], [PubMed], [CAS], Google Scholar
      7
      A microdroplet-accelerated Biginelli reaction: mechanisms and separation of isomers using IMS-MS
      Sahota, Navneet; AbuSalim, Deyaa I.; Wang, Melinda L.; Brown, Christopher J.; Zhang, Zhicaho; El-Baba, Tarick J.; Cook, Silas P.; Clemmer, David E.
      Chemical Science (2019), 10 (18), 4822-4827CODEN: CSHCCN; ISSN:2041-6520. (Royal Society of Chemistry)
      Electrospray ionization (ESI) combined with ion mobility spectrometry (IMS) and mass spectrometry (MS) techniques is used to examine the Biginelli reaction in an ensemble of ions generated from droplets. We find evidence for rapid dihydropyrimidinone formation from condensation of Et acetoacetate, benzaldehyde, and urea on the very short timescales assocd. with the electrospray process (∼10 μs to ∼1.0 ms). Control bulk-soln. reactions show no product formation even after several days. This implies that the in-droplet reaction rate is enhanced by an astonishing factor. Examn. of the reaction conditions and characterization of the intermediates en route to product shows evidence for variations in the reaction mechanism. IMS sepn. shows that the Knoevenagel condensation intermediate from benzaldehyde and Et acetoacetate exists as both the cis- and trans-isomer, in a ∼5 to 1 ratio. We suggest that the dramatic acceleration arises because of increased reagent confinement as electrosprayed droplets shrink. The ability of IMS-MS to resolve intermediates (including isomers) provides a new means of understanding reaction pathways.
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    8. 8
      Lee, J. K.; Walker, K. L.; Han, H. S.; Kang, J.; Prinz, F. B.; Waymouth, R. M.; Nam, H. G.; Zare, R. N. Spontaneous Generation of Hydrogen Peroxide from Aqueous Microdroplets. Proc. Natl. Acad. Sci. U. S. A. 2019, 116 (39), 19294– 19298,  DOI: 10.1073/pnas.1911883116
      [Crossref], [PubMed], [CAS], Google Scholar
      8
      Spontaneous generation of hydrogen peroxide from aqueous microdroplets
      Lee, Jae Kyoo; Walker, Katherine L.; Han, Hyun Soo; Kang, Jooyoun; Prinz, Fritz B.; Waymouth, Robert M.; Nam, Hong Gil; Zare, Richard N.
      Proceedings of the National Academy of Sciences of the United States of America (2019), 116 (39), 19294-19298CODEN: PNASA6; ISSN:0027-8424. (National Academy of Sciences)
      We show H2O2 is spontaneously produced from pure water by atomizing bulk water into microdroplets (1μm to 20μm in diam.). Prodn. of H2O2, as assayed by H2O2-sensitive fluorescence dye peroxyfluor-1, increased with decreasing microdroplet size. Cleavage of 4-carboxyphenylboronic acid and conversion of phenylboronic acid to phenols in microdroplets further confirmed the generation of H2O2. The generated H2O2 concn. was ≈30μM (≈1 part per million) as detd. by titrn. with potassium titanium oxalate. Changing the spray gas to O2 or bubbling O2 decreased the yield of H2O2 in microdroplets, indicating that pure water microdroplets directly generate H2O2 without help from O2 either in air surrounding the droplet or dissolved in water. We consider various possible mechanisms for H2O2 formation and report a no. of different expts. exploring this issue. We suggest that hydroxyl radical (OH) recombination is the most likely source, in which OH is generated by loss of an electron from OH- at or near the surface of the water microdroplet. This catalyst-free and voltage-free H2O2 prodn. method provides innovative opportunities for green prodn. of hydrogen peroxide.
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    9. 9
      Spencer, S. E.; Tyler, C. A.; Tolocka, M. P.; Glish, G. L. Low-Temperature Plasma Ionization-Mass Spectrometry for the Analysis of Compounds in Organic Aerosol Particles. Anal. Chem. 2015, 87 (4), 2249– 2254,  DOI: 10.1021/ac5038889
      [ACS Full Text ACS Full Text], [CAS], Google Scholar
      9
      Low-Temperature Plasma Ionization-Mass Spectrometry for the Analysis of Compounds in Organic Aerosol Particles
      Spencer, Sandra E.; Tyler, Chelsea A.; Tolocka, Michael P.; Glish, Gary L.
      Analytical Chemistry (Washington, DC, United States) (2015), 87 (4), 2249-2254CODEN: ANCHAM; ISSN:0003-2700. (American Chemical Society)
      Low-temp. plasma ionization, a technique that causes minimal fragmentation during ionization, is investigated as an ionization technique for mass spectrometric detection of the compds. in ambient org. aerosols in real time. The expts. presented in this paper demonstrate that ions are generated from compds. in the aerosol particles. The utility of this technique for detection of both pos. and neg. ions from the pyrolyzate of multiple natural polymers (Et cellulose, cellulose, and lignin) is presented. Ultimately, low-temp. plasma ionization is shown to be a promising ionization technique for detection of compds. in org. aerosols by mass spectrometry.
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    10. 10
      Swanson, K. D.; Worth, A. L.; Glish, G. L. Use of an Open Port Sampling Interface Coupled to Electrospray Ionization for the On-Line Analysis of Organic Aerosol Particles. J. Am. Soc. Mass Spectrom. 2018, 29 (2), 297– 303,  DOI: 10.1007/s13361-017-1776-y
      [ACS Full Text ACS Full Text], [CAS], Google Scholar
      10
      Use of an Open Port Sampling Interface Coupled to Electrospray Ionization for the On-Line Analysis of Organic Aerosol Particles
      Swanson, Kenneth D.; Worth, Anne L.; Glish, Gary L.
      Journal of the American Society for Mass Spectrometry (2018), 29 (2), 297-303CODEN: JAMSEF; ISSN:1044-0305. (Springer)
      A simple design for an open port sampling interface coupled to electrospray ionization (OPSI-ESI) is presented for the anal. of org. aerosols. The design uses minimal modifications to a Bruker electrospray (ESI) emitter to create a continuous flow, self-aspirating open port sampling interface. Considerations are presented for introducing aerosol to the open port sampling interface including aerosol gas flow and solvent flow rates. The device was demonstrated for use with an aerosol of nicotine as well as aerosol formed in the pyrolysis of biomass. Upon comparison with extractive electrospray ionization (EESI), this device has similar sensitivity with increased reproducibility by nearly a factor of three. The device has the form factor of a std. Bruker/Agilent ESI emitter and can be used without any further instrument modifications. [Figure not available: see fulltext.].
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    11. 11
      Canagaratna, M. R.; Jayne, J. T.; Jimenez, J. L.; Allan, J. D.; Alfarra, M. R.; Zhang, Q.; Onasch, T. B.; Drewnick, F.; Coe, H.; Middlebrook, A. Chemical and Microphysical Characterization of Ambient Aerosols with the Aerodyne Aerosol Mass Spectrometer. Mass Spectrom. Rev. 2007, 26 (2), 185– 222,  DOI: 10.1002/mas.20115
      [Crossref], [PubMed], [CAS], Google Scholar
      11
      Chemical and microphysical characterization of ambient aerosols with the aerodyne aerosol mass spectrometer
      Canagaratna, M. R.; Jayne, J. T.; Jimenez, J. L.; Allan, J. D.; Alfarra, M. R.; Zhang, Q.; Onasch, T. B.; Drewnick, F.; Coe, H.; Middlebrook, A.; Delia, A.; Williams, L. R.; Trimborn, A. M.; Northway, M. J.; DeCarlo, P. F.; Kolb, C. E.; Davidovits, P.; Worsnop, D. R.
      Mass Spectrometry Reviews (2007), 26 (2), 185-222CODEN: MSRVD3; ISSN:0277-7037. (John Wiley & Sons, Inc.)
      A review. The application of mass spectrometric techniques to the real-time measurement and characterization of aerosols represents a significant advance in the field of atm. science. This review focuses on the aerosol mass spectrometer (AMS), an instrument designed and developed at Aerodyne Research, Inc. (ARI) that is the most widely used thermal vaporization AMS. The AMS uses aerodynamic lens inlet technol. together with thermal vaporization and electron-impact mass spectrometry to measure the real-time non-refractory (NR) chem. speciation and mass loading as a function of particle size of fine aerosol particles with aerodynamic diams. between ∼50 and 1,000 nm. The original AMS utilizes a quadrupole mass spectrometer (Q) with electron impact (EI) ionization and produces ensemble av. data of particle properties. Later versions employ time-of-flight (ToF) mass spectrometers and can produce full mass spectral data for single particles. This manuscript presents a detailed discussion of the strengths and limitations of the AMS measurement approach and reviews how the measurements are used to characterize particle properties. Results from selected lab. expts. and field measurement campaigns are also presented to highlight the different applications of this instrument. Recent instrumental developments, such as the incorporation of softer ionization techniques (vacuum UV (VUV) photo-ionization, Li+ ion, and electron attachment) and high-resoln. ToF mass spectrometers, that yield more detailed information about the org. aerosol component are also described.
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    12. 12
      McMurry, P. A Review of Atmospheric Aerosol Measurements. Atmos. Environ. 2000, 34 (12–14), 1959– 1999,  DOI: 10.1016/S1352-2310(99)00455-0
      [Crossref], [CAS], Google Scholar
      12
      A review of atmospheric aerosol measurements
      McMurry, Peter H.
      Atmospheric Environment (2000), 34 (12-14), 1959-1999CODEN: AENVEQ; ISSN:1352-2310. (Elsevier Science Ltd.)
      Recent developments in atm. aerosol measurements are reviewed with many refs. The topics included complement those covered in the recent review by Chow which focuses on regulatory compliance measurements and filter measurements of particulate compn. This review focuses on measurements of aerosol integral properties (total no. concn., CCN concn., optical coeffs., etc.), aerosol phys. chem. properties (d., refractive index, equil. water content, etc.), measurements of aerosol size distributions, and measurements of size-resolved aerosol compn. Such measurements play an essential role in studies of secondary aerosol formation by atm. chem. transformations and enable one to quantify the contributions of various species to effects including light scattering/absorption, health effects, dry deposition, etc. Aerosol measurement evolved from an art to a science in the 1970s following the development of instrumentation to generate monodisperse calibration aerosols of known size, compn., and concn. While such calibration tools permit precise assessments of instrument responses to known lab.-generated aerosols, unquantifiable uncertainties remain even when carefully calibrated instruments are used for atm. measurements. This is because instrument responses typically depend on aerosol properties including compn., shape, d., etc., which, for atm. aerosols, may vary from particle-to-particle and are often unknown. More effort needs to be made to quantify measurement accuracies that can be achieved for realistic atm. sampling scenarios. The measurement of org. species in atm. particles requires substantial development. Atm. aerosols typically include hundreds of org. compds., and only a small fraction (∼ 10%) of these can be identified by state-of-the-art anal. methodologies. Even the measurement of the total particulate org. carbon mass concn. is beset by difficulties including the unknown extent of evaporative losses during sampling, adsorption of gas-phase org. compds. onto sampling substrates, and the unknown relationship between carbon mass and mass of the particulate orgs. The development of improved methodologies for such measurements should be a high priority for the future. Mass spectrometers that measure the compn. of individual particles have recently been developed. It is not clear that these instruments will provide quant. information on species mass concns., and more work is needed to routinely interpret the vast quantities of data generated during field sampling. Nevertheless, these instruments substantially expand the range of atm. aerosol issues that can be explored exptl. These instruments represent the most significant advance in aerosol instrumentation in recent years.
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    13. 13
      Bateman, A. P.; Nizkorodov, S. A.; Laskin, J.; Laskin, A. High-Resolution Electrospray Ionization Mass Spectrometry Analysis of Water-Soluble Organic Aerosols Collected with a Particle into Liquid Sampler. Anal. Chem. 2010, 82 (19), 8010– 8016,  DOI: 10.1021/ac1014386
      [ACS Full Text ACS Full Text], [CAS], Google Scholar
      13
      High-Resolution Electro-spray Ionization Mass Spectrometry Analysis of Water-Soluble Organic Aerosols Collected with a Particle into Liquid Sampler
      Bateman, Adam P.; Nizkorodov, Sergey A.; Laskin, Julia; Laskin, Alexander
      Analytical Chemistry (Washington, DC, United States) (2010), 82 (19), 8010-8016CODEN: ANCHAM; ISSN:0003-2700. (American Chemical Society)
      This work demonstrated the utility of a particle-into-liq. sampler (PILS), a technique traditionally used to identify inorg. ions present in ambient or lab. aerosols, for anal. of water-sol. org. aerosol (OA) by high-resoln. electro-spray ionization mass spectrometry (HR-ESI-MS). Secondary org. aerosol (SOA) was produced from 0.5 ppm mixing ratios of limonene and O3 in a 5 m3 Teflon chamber. SOA was simultaneously collected using a traditional filter sampler and a PILS. Filter samples were extd. with water or acetonitrile; the aq. PILS samples were directly analyzed. In terms of peak abundance, types of detectable compds., av. O:C ratio, and org. mass:org. C ratio, the resulting high-resoln. mass spectra were essentially identical for PILS- and filter-based samples. SOA compds. extd. from filter/acetonitrile extn. and PILS/water extn. accounted for >95% of the total ion current in ESI mass spectra. This similarity was attributed to high soly. of limonene SOA in water. Significant differences in detected ions and peak abundance were obsd. for pine needle biomass burning org. aerosol (BBOA) collected with PILS and filter sampling. The BBOA water-sol. fraction was considerably smaller than for SOA, and several unique peaks were detectable only with the filter/acetonitrile method. The combination of PILS collection with HR-ESI-MS anal. offers a new approach for mol. anal. of the water-sol. org. fraction in biogenic SOA, aged photochem. smog, and BBOA.
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    14. 14
      Tang, H.; Hiemstra, S.; Thompson, J. E. Characterization of a Novel Particle into Liquid Sampler for Analysis of Single Fluorescent Aerosol Particles through Capillary Electrophoresis. Anal. Chim. Acta 2011, 702 (1), 120– 126,  DOI: 10.1016/j.aca.2011.06.029
      [Crossref], [PubMed], [CAS], Google Scholar
      14
      Characterization of a novel particle into liquid sampler for analysis of single fluorescent aerosol particles through capillary electrophoresis
      Tang, Hao; Hiemstra, Scott; Thompson, Jonathan E.
      Analytica Chimica Acta (2011), 702 (1), 120-126CODEN: ACACAM; ISSN:0003-2670. (Elsevier B.V.)
      An approach to sample and analyze single aerosolized droplets (<10 nL) of solns. contg. fluorescein isothiocyanate (FITC)-labeled glycine (GLY) and glutamic acid (GLU) was demonstrated. This sampling approach is based on inertial impaction in which the sample particle is accelerated through a nozzle and directly into a small drop of buffered soln. (20 mM borate, pH = 10) suspended at the end of a coaxial stainless steel tube with a fused SiO2 capillary. A spherical light scattering cell and laser (λ = 532 nm) detects the particle arrival at the buffered droplet. Upon dissoln. and/or mixing, a portion of the sample is injected onto the fused SiO2 capillary for subsequent chem. anal. by capillary electrophoresis (CE) with laser-induced fluorescence detection. The inertial impaction approach sampled particles >1 μm diam. with an efficiency ≥80%. At 15 kV applied potential, the FITC GLY and GLU conjugates could be resolved in <120 s, allowing qual. anal. of the contents of single dispersed particles; however, the extent to which the sample is dild. in the buffer droplet varied significantly on a per-particle basis, causing a >80% relative std. deviation in fluorescence peak heights. This aspect of the method necessitates using internal stds. to quant. analyze materials present within the particles. It is envisaged that further improvements to the described device may ultimately lead to anal. of the contents of single particles dispersed in the earth atm.
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    15. 15
      Wang, Z.; DeWitt, J. C.; Higgins, C. P.; Cousins, I. T. A Never-Ending Story of Per- and Polyfluoroalkyl Substances (PFASs)?. Environ. Sci. Technol. 2017, 51, 2508– 2518,  DOI: 10.1021/acs.est.6b04806
      [ACS Full Text ACS Full Text], [CAS], Google Scholar
      15
      A Never-Ending Story of Per- and Polyfluoroalkyl Substances (PFASs)?
      Wang, Zhanyun; DeWitt, Jamie C.; Higgins, Christopher P.; Cousins, Ian T.
      Environmental Science & Technology (2017), 51 (5), 2508-2518CODEN: ESTHAG; ISSN:0013-936X. (American Chemical Society)
      A review. More than 3000 per- and polyfluoroalkyl substances (PFASs) are, or have been, on the global market, yet most research and regulation continues to focus on a limited selection of rather well-known long-chain PFASs, particularly perfluorooctanesulfonate (PFOS), perfluorooctanoic acid (PFOA) and their precursors. Continuing to overlook the vast majority of other PFASs is a major concern for society. We provide recommendations for how to proceed with research and cooperation to tackle the vast no. of PFASs on the market and in the environment.
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    16. 16
      Kazemi, R.; Potts, E. I.; Dick, J. E. Quantifying Interferent Effects on Molecularly Imprinted Polymer Sensors for Per- And Polyfluoroalkyl Substances (PFAS). Anal. Chem. 2020, 92 (15), 10597– 10605,  DOI: 10.1021/acs.analchem.0c01565
      [ACS Full Text ACS Full Text], [CAS], Google Scholar
      16
      Quantifying interferent effects on molecularly imprinted polymer sensors for per- and polyfluoroalkyl substances (PFAS)
      Kazemi, Rezvan; Potts, Emili I.; Dick, Jeffrey E.
      Analytical Chemistry (Washington, DC, United States) (2020), 92 (15), 10597-10605CODEN: ANCHAM; ISSN:0003-2700. (American Chemical Society)
      Per- and polyfluoroalkyl substances (PFAS) are emerging as harmful environmental micropollutants. Generally, PFAS species are quantified by mass spectrometry, for which a collected sample is taken to a centralized facility. Robust techniques to quantify PFAS in the field are necessary to diagnose environmental contamination at the earliest onset of pollution. Here, we developed a molecularly imprinted polymer (MIP) electrode for the detection of perfluorooctanesulfonate (PFOS) and explored the MIP surface and the effects of interfering mols. MIPs were formed by the anodic deposition of o-phenylenediamine (o-PD) in the presence of PFOS template mols. on a glassy carbon macroelectrode. The performance of the resulting MIP electrode was evaluated by the current obtained from the oxidn. of ferrocene carboxylic acid as the electrochem. probe. The MIP electrode was able to detect PFOS with a detection limit of 0.05 nM, which is lower than the health advisory limit of 0.14 nM reported by the U.S. EPA. To better understand PFOS assocn. into the MIP, a Langmuir binding model was developed based on the changes in electrochem. responses of the MIP. Fitting the model to the exptl. data gave an assocn. const. (KA) of 4.95 x 1012 over a PFOS concn. range of 0 to 0.05 nM. The binding isotherm of other commonly found substances in contaminated water sources such as chloride, humic acid, perfluorooctanoic acid (PFOA), and perfluorobutanesulfonate (PFBS) was also investigated. In the case of chloride and humic acid, the calcd. KA values of 9.05 x 107 and 6.01 x 105, resp., indicate relatively weak adsorption of these species on the MIP. However, PFOA, which is the carboxylate analog of PFOS, revealed a very close KA value (3.41 x 1012) to PFOS. A greater KA value (1.43 x 1013) was obtained for PFBS, which possesses the same functional group and a smaller mol. size compared to PFOS. The presented platform emphasizes the necessity to develop new strategies to make MIP sensors more specific if practical applications are to be pursued.
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    17. 17
      Karimian, N.; Stortini, A. M.; Moretto, L. M.; Costantino, C.; Bogialli, S.; Ugo, P. Electrochemosensor for Trace Analysis of Perfluorooctanesulfonate in Water Based on a Molecularly Imprinted Poly(o-Phenylenediamine) Polymer. ACS Sensors 2018, 3 (7), 1291– 1298,  DOI: 10.1021/acssensors.8b00154
      [ACS Full Text ACS Full Text], [CAS], Google Scholar
      17
      Electrochemosensor for Trace Analysis of Perfluorooctanesulfonate in Water Based on a Molecularly Imprinted Poly(o-phenylenediamine) Polymer
      Karimian, Najmeh; Stortini, Angela M.; Moretto, Ligia M.; Costantino, Claudio; Bogialli, Sara; Ugo, Paolo
      ACS Sensors (2018), 3 (7), 1291-1298CODEN: ASCEFJ; ISSN:2379-3694. (American Chemical Society)
      This work is aimed at developing an electrochem. sensor for the sensitive and selective detection of trace levels of perfluorooctanesulfonate (PFOS) in water. Contamination of waters by perfluorinated alkyl substances (PFAS) is a problem of global concern due to their suspected toxicity and ability to bioaccumulate. PFOS is the perfluorinated compd. of major concern, as it has the lowest suggested control concns. The sensor reported here is based on a gold electrode modified with a thin coating of a molecularly imprinted polymer (MIP), prepd. by anodic electropolymn. of o-phenylenediamine (o-PD) in the presence of PFOS as the template. Activation of the sensor is achieved by template removal with suitable a solvent mixt. Voltammetry, a quartz crystal microbalance, SEM and elemental anal. were used to monitor the electropolymn. process, template removal, and binding of the analyte. Ferrocenecarboxylic acid (FcCOOH) has been exploited as an electrochem. probe able to generate anal. useful voltammetric signals by competing for the binding sites with PFOS, as the latter is not electroactive. The sensor has a low detection limit (0.04 nM), a satisfactory selectivity, and is reproducible and repeatable, giving anal. results in good agreement with those obtained by HPLC-MS/MS analyses.
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    18. 18
      Clark, R. B.; Dick, J. E. Electrochemical Sensing of Perfluorooctanesulfonate (PFOS) Using Ambient Oxygen in River Water. ACS Sensors 2020, 5 (11), 3591– 3598,  DOI: 10.1021/acssensors.0c01894
      [ACS Full Text ACS Full Text], [CAS], Google Scholar
      18
      Electrochemical sensing of perfluorooctanesulfonate (PFOS) using ambient oxygen in river water
      Clark, Rebecca B.; Dick, Jeffrey E.
      ACS Sensors (2020), 5 (11), 3591-3598CODEN: ASCEFJ; ISSN:2379-3694. (American Chemical Society)
      Per- and polyfluoroalkyl substances (PFAS) are an emerging class of pervasive and harmful micropollutant. Next-generation sensors are necessary to detect PFAS at sub-nanomolar levels. Electrochem. can measure analyte concns. at sub-10 nM levels and offers a deployable platform; however, the lack of chem. reactivity of PFAS species requires electrode surface functionalization with a molecularly imprinted polymer (MIP). Previously, such sensors have required a well-characterized one-electron mediator (i.e., ferrocene carboxylic acid or ferrocene methanol) for detection. Natural waterways do not have an abundance of ferrocenyl compds. for quantification, implying that these mediators limit sensor practicality, deployability, and cost. Here, we take advantage of ambient oxygen present in river water to quantify one of the more harmful PFAS mols., perfluorooctanesulfonate (PFOS), from 0 to 0.5 nM on a MIP-modified carbon substrate. Differential pulse voltammetry (DPV) and electrochem. impedance spectroscopy (EIS) generated calibration curves for PFOS in river water using oxygen as the mediator. Importantly, we show that electrochem. impedance spectroscopy is superior to voltammetric techniques: like ultramicroelectrodes, this technique can be used in low-cond. matrixes like river water with high reproducibility. Further, impedance provides a PFOS limit of detection of 3.4 pM. We also demonstrate that the common interferents humic acid and chloride do not affect the sensor signal. These results are a necessary step forward in developing deployable sensors that act as a first line of defense for detecting PFAS contamination at its earliest onset.
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    19. 19
      Glasscott, M. W.; Vannoy, K. J.; Kazemi, R.; Verber, M. D.; Dick, J. E. μ-MIP: Molecularly Imprinted Polymer-Modified Microelectrodes for the Ultrasensitive Quantification of GenX (HFPO-DA) in River Water. Environ. Sci. Technol. Lett. 2020, 7 (7), 489– 495,  DOI: 10.1021/acs.estlett.0c00341
      [ACS Full Text ACS Full Text], [CAS], Google Scholar
      19
      μ-MIP: Molecularly Imprinted Polymer-Modified Microelectrodes for the Ultrasensitive Quantification of GenX (HFPO-DA) in River Water
      Glasscott, Matthew W.; Vannoy, Kathryn J.; Kazemi, Rezvan; Verber, Matthew D.; Dick, Jeffrey E.
      Environmental Science & Technology Letters (2020), 7 (7), 489-495CODEN: ESTLCU; ISSN:2328-8930. (American Chemical Society)
      Per- and polyfluoroalkyl substances (PFAS) are emerging as a hazardous class of environmental micropollutant, and robust, sensitive, and inexpensive sensing modalities are needed to detect the earliest onset of contamination of surface water. Here, the authors present a molecularly imprinted polymer (MIP)-modified microelectrode (r = 6.25 μm) sensor for the quantification of a pervasive environmental PFAS, GenX (HFPO-DA), in surface water obtained from the Haw River in North Carolina. A 20 nm film of o-phenylenediamine was electropolymd. in the presence of GenX to generate a templated polymer adjacent to the electrode surface with subsequent solvent extn. resulting in GenX-specific recognition sites. The oxidn. of ferrocene methanol was obsd. as a function of GenX concn., and the current decreased linearly with the concn. of GenX. A linear dynamic range of 1-5000 pM with a limit of detection of 250 fM and excellent selectivity against environmental interferents, such as humic acid and perfluorooctanesulfonate, was achieved. The use of oxygen redn. as an addnl. ambient detection mechanism and the amenability of microelectrodes to relatively resistive environmental matrixes extend the applicability of MIP-modified microelectrodes to environmental waterways as deployable sensors.
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    20. 20
      Kwak, J.; Bard, A. J. Scanning Electrochemical Microscopy. Theory of the Feedback Mode. Anal. Chem. 1989, 61 (11), 1221– 1227,  DOI: 10.1021/ac00186a009
      [ACS Full Text ACS Full Text], [CAS], Google Scholar
      20
      Scanning electrochemical microscopy. Theory of the feedback mode
      Kwak, Juhyoun; Bard, Allen J.
      Analytical Chemistry (1989), 61 (11), 1221-7CODEN: ANCHAM; ISSN:0003-2700.
      The steady-state current that flows between the scanning tip (a disk ultramicroelectrode imbedded in an insulating sheath) and a planar sample substrate in a scanning electrochem. microscope (SECM) operating in the feedback mode was calcd. by the finite element method with an exponentially expanding grid, for both conductive and insulating samples. For conductive substrates the tip current, representing, for example, the oxidn. reaction of R to O, is enhanced by flow of R generated at the substrate to the tip and is a function of tip/substrate distance, d, but not the radius of the insulating sheath. For insulating substrates, the tip current is decreased by blockage of the diffusion of R to the tip by the substrate and depends upon d and the insulating sheath radius. The theor. results were compared to exptl. studies.
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    21. 21
      Wright, T. P.; Song, C.; Sears, S.; Petters, M. D. Thermodynamic and Kinetic Behavior of Glycerol Aerosol. Aerosol Sci. Technol. 2016, 50 (12), 1385– 1396,  DOI: 10.1080/02786826.2016.1245405
      [Crossref], [CAS], Google Scholar
      21
      Thermodynamic and kinetic behavior of glycerol aerosol
      Wright, Timothy P.; Song, Chen; Sears, Stephen; Petters, Markus D.
      Aerosol Science and Technology (2016), 50 (12), 1385-1396CODEN: ASTYDQ; ISSN:0278-6826. (Taylor & Francis, Inc.)
      Glycerol and propylene glycol mixts. are common carrier solns. in electronic cigarettes. Aerosols produced from these mixts. will evap. quickly in a dry environment due to their high volatility. In a humid environment, such as the lungs, the kinetics of evapn. and hygroscopic growth det. the evolution of aerosol plume glycerol. Here, we apply a temp. and relative humidity-controlled hygroscopicity/volatility tandem differential mobility analyzer system to study the growth and evapn. kinetics of glycerol aerosol over a wide range of temp., relative humidity, and residence times. Results show that at dry conditions glycerol aerosols evap. within seconds at temps. warmer than 20°C and that the accommodation coeff. of glycerol vapor on dry glycerol particles is 0.8. Under humidified conditions, the mutual depression of vapor pressures of the aq. glycerol/water soln. slows the glycerol evapn. rate consistent with thermodn. and kinetic model predictions. Model calcns. show that water vapor aided condensation of glycerol can occur at high relative humidity for glycerol vapor concns. that result in glycerol particle evapn. under dry conditions. The combined results will help with constraining computational modules that model the evolution of glycerol-contg. aerosols along a prescribed thermodn. trajectory. Copyright 2016 American Assocn. for Aerosol Research.
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    22. 22
      Demokritou, P.; Kavouras, I. G.; Ferguson, S. T.; Koutrakis, P. Development of a High Volume Cascade Impactor for Toxicological and Chemical Characterization Studies. Aerosol Sci. Technol. 2002, 36 (9), 925– 933,  DOI: 10.1080/02786820290092113
      [Crossref], [CAS], Google Scholar
      22
      Development of a high volume cascade impactor for toxicological and chemical characterization studies
      Demokritou, P.; Kavouras, I. G.; Ferguson, S. T.; Koutrakis, P.
      Aerosol Science and Technology (2002), 36 (9), 925-933CODEN: ASTYDQ; ISSN:0278-6826. (Taylor & Francis Inc.)
      This paper presents the design and development of a compact high-vol. cascade impactor (HVCI). The HVCI operates at a flow rate of 900 L/min and consists of 4 impaction stages equipped with circular slit-shaped acceleration nozzles and a backup filter. The backup filter is placed downstream of the fourth stage and is used to collect the ultrafine particles (particle size <0.1 μm). The major feature of this novel sampler is its ability to collect relatively large amts. of particles (milligram-gram levels) onto relatively small polyurethane foam substrates without using adhesives. As previously reported, the capacity of the impaction substrate is 2.15 g of collected particles per cm2 of foam. Although the impaction substrates are not coated with adhesives such as grease or mineral oil, particle bounce and re-entrainment losses were found not to be significant. Particles can be easily recovered from the foam substrates using aq. extn. The impactor was calibrated using polydisperse particles. The 50% cutpoints of the 4 stages were 9.90, 2.46, 1.0, and 0.1 μm, resp. Interstage losses of ultrafine and fine particles were <10% and for coarse particles were <20%. The pressure drop across the 4 stages and the backup filter were 0.25, 0.75, 1.25, 19.9, and 3.3 kPa, resp.
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    23. 23
      John, W.; Reischl, G. A Cyclone for Size-Selective Sampling of Ambient Air. J. Air Pollut. Control Assoc. 1980, 30 (8), 872– 876,  DOI: 10.1080/00022470.1980.10465122
      [Crossref], [CAS], Google Scholar
      23
      A cyclone for size-selective sampling of ambient air
      John, Walter; Reischl, Georg
      Journal of the Air Pollution Control Association (1980), 30 (8), 872-6CODEN: JPCAAC; ISSN:0002-2470.
      A cyclone with a 47 mm after-filter has been developed for ambient air size-selective monitoring. It has been extensively evaluated with lab.-generated aerosol. Variation of the pressure drop and 50% cut point with flow rate show that th cyclone operates in a single flow regime with a vortex in the outlet flow. The particle size cutoff curve is comparable in sharpness to a cascade impactor and is the same for solid or liq. particles. At 21.7 L/min, the 50% particle diam. cutoff (D50) is 2.5 and at 15.4 L/min, D50 is 3.5 μm. Collection efficiency data for flow of 8-27 L/min fit a universal curve when plotted vs. the normalized particle diam., (D-D50)/D50. Reentrainment of previously deposited particles is <1% of the loading/day.
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    24. 24
      Salcedo, D.; Onasch, T. B.; Aiken, A. C.; Williams, L. R.; De Foy, B.; Cubison, M. J.; Worsnop, D. R.; Molina, L. T.; Jimenez, J. L. Determination of Particulate Lead Using Aerosol Mass Spectrometry: MILAGRO/MCMA-2006 Observations. Atmos. Chem. Phys. 2010, 10 (12), 5371– 5389,  DOI: 10.5194/acp-10-5371-2010
      [Crossref], Google Scholar
      There is no corresponding record for this reference.
    25. 25
      Tsai, C. J.; Shih, T. S.; Sheu, R. N. Characteristics of Lead Aerosols in Different Work Environments. Am. Ind. Hyg. Assoc. J. 1997, 58 (9), 650– 656,  DOI: 10.1080/15428119791012441
      [Crossref], [PubMed], [CAS], Google Scholar
      25
      Characteristics of lead aerosols in different work environments
      Tsai, Chuen-Jinn; Shih, Tung-Sheng; Sheu, Rong-Nan
      American Industrial Hygiene Association Journal (1997), 58 (9), 650-656CODEN: AIHAAP; ISSN:0002-8894. (American Industrial Hygiene Association)
      Air samples were collected to examine phys. and chem. characteristics of Pb aerosols in different work environments in the airborne Pb concn. of 28-783 μg/m3. Size distribution of aerosols was measured using a Marple personal cascade impactor, and Pb anal. was conducted using graphite at. absorption spectrometry. Pb aerosol size distribution was different from that of total particles. Such differences are not negligible and must be taken into account when estg. aerosol deposition within the human respiratory tract. Variation of MMAD (mass median aerodynamic diam.) and GSD (geometric std. deviation) of Pb aerosols in the coarse mode with total airborne concn. was small, and the assumption that Pb aerosol distribution is const. is reasonable for establishing the relationship between airborne Pb and blood Pb concns. Respirable Pb concn. was well correlated with the total airborne Pb concn. in all work areas of the three plants except the charging area of the capacitor plant. Therefore, it is expected that either total airborne Pb or respirable airborne Pb concn. can be used to correlate blood Pb concn.
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    26. 26
      U. S. EPA Review of the National Ambient Air Quality Standards for Lead 2016, 81, 845,  DOI: 10.1002/9781119117896.ch68
      [Crossref], Google Scholar
      There is no corresponding record for this reference.
    27. 27
      Sorooshian, A.; Brechtel, F. J.; Ma, Y.; Weber, R. J.; Corless, A.; Flagan, R. C.; Seinfeld, J. H. Modeling and Characterization of a Particle-into-Liquid Sampler (PILS). Aerosol Sci. Technol. 2006, 40 (6), 396– 409,  DOI: 10.1080/02786820600632282
      [Crossref], [CAS], Google Scholar
      27
      Modeling and Characterization of a Particle-into-Liquid Sampler (PILS)
      Sorooshian, Armin; Brechtel, Fred; Ma, Yilin; Weber, Rodney; Corless, Andrew; Flagan, Richard; Seinfeld, John
      Aerosol Science and Technology (2006), 40 (6), 396-409CODEN: ASTYDQ; ISSN:0278-6826. (Taylor & Francis, Inc.)
      A modified particle-into-liq. sampler (PILS), based on the original design of R.J. Weber, et al. (2001), is discussed. The principal modification in this design is that collected liq. sample is delivered to vials held on a rotating carousel vs. an online anal. detector. A model was developed to predict aerosol mass concns. measured by a PILS based on sampled aerosol operating parameters and characteristics. A backward model predicted sampled aerosol concns. based on operating parameters and concns. measured by PILS. Both models, which consider plumbing transmission efficiency, droplet growth, mixing effects, and volatilization loss, predicted mass concns. which were consistent with lab. tests for concn. step changes. Av. collection efficiency for species (Na+, K+, SO42-, Cl-, NO3-) from a variety of aerosols vs. simultaneous measurements with a differential mobility analyzer (DMA) exceeded 96% except for NH4+ (88%); NH4+ was theor. shown to be the most vulnerable to volatilization, followed by Cl- and NO3-, with greater losses caused by increasing droplet pH and temp. Characterization tests highlighted the importance of reducing NH4+ volatilization by keeping a stable tip temp. of 100° at the point where steam and ambient air mix in the condensation chamber. Maintaining a stable tip temp. also avoided fluctuations in super-saturations which led to increased deposition losses of larger droplets. Sample data from the 2004 International Consortium for Atm. Research on Transport and Transformation field campaign are presented.
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    28. 28
      Fukami, C. S.; Sullivan, A. P.; Ryan Fulgham, S.; Murschell, T.; Borch, T.; Smith, J. N.; Farmer, D. K. Technical Note: An Improved Approach to Determining Background Aerosol Concentrations with PILS Sampling on Aircraft. Atmos. Environ. 2016, 136, 16– 20,  DOI: 10.1016/j.atmosenv.2016.04.005
      [Crossref], [CAS], Google Scholar
      28
      Technical note: An improved approach to determining background aerosol concentrations with PILS sampling on aircraft
      Fukami, Christine S.; Sullivan, Amy P.; Ryan Fulgham, S.; Murschell, Trey; Borch, Thomas; Smith, James N.; Farmer, Delphine K.
      Atmospheric Environment (2016), 136 (), 16-20CODEN: AENVEQ; ISSN:1352-2310. (Elsevier Ltd.)
      Particle-into-Liq. Samplers (PILS) have become a std. aerosol collection technique, and are widely used in both ground and aircraft measurements in conjunction with off-line ion chromatog. (IC) measurements. Accurate and precise background samples are essential to account for gas-phase components not efficiently removed and any interference in the instrument lines, collection vials or off-line anal. procedures. For aircraft sampling with PILS, backgrounds are typically taken with in-line filters to remove particles prior to sample collection once or twice per flight with more numerous backgrounds taken on the ground. Here, we use data collected during the Front Range Air Pollution and Photochem. E´xperiment (FRAPPE´) to demonstrate that not only are multiple background filter samples are essential to attain a representative background, but that the chem. background signals do not follow the Gaussian statistics typically assumed. Instead, the background signals for all chem. components analyzed from 137 background samples (taken from ∼78 total sampling hours over 18 flights) follow a log-normal distribution, meaning that the typical approaches of averaging background samples and/or assuming a Gaussian distribution cause an over-estn. of background samples - and thus an underestimation of sample concns. Our approach of deriving backgrounds from the peak of the log-normal distribution results in detection limits of 0.25, 0.32, 3.9, 0.17, 0.75 and 0.57 μg m-3 for sub-micron aerosol nitrate (NO-3), nitrite (NO-2), ammonium (NH+4), sulfate (SO2-4), potassium (K+) and calcium (Ca2+), resp. The difference in backgrounds calcd. from assuming a Gaussian distribution vs. a log-normal distribution were most extreme for NH+4, resulting in a background that was 1.58× that detd. from fitting a log-normal distribution.
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    29. 29
      Pétré, M.-A.; Koropeckyj-Cox, L.; Duboscq, S. M.; Genereux, D. P.; Knappe, D. R. U.; Gilmore, T. E.; Hopkins, Z. R. Per- and Polyfluoroalkyl Substance (Pfas) Transport From Groundwater To Streams Near a Pfas Manufacturing Facility in North Carolina, Usa. Environ. Sci. Technol. 2021, 55 (9), 5848– 5856,  DOI: 10.1021/acs.est.0c07978
      [ACS Full Text ACS Full Text], [CAS], Google Scholar
      29
      Per- and polyfluoroalkyl substance (PFAS) transport from groundwater to streams near a PFAS manufacturing facility in North Carolina, USA
      Petre, Marie-Amelie; Genereux, David P.; Koropeckyj-Cox, Lydia; Knappe, Detlef R. U.; Duboscq, Sandrine; Gilmore, Troy E.; Hopkins, Zachary R.
      Environmental Science & Technology (2021), 55 (9), 5848-5856CODEN: ESTHAG; ISSN:0013-936X. (American Chemical Society)
      We quantified per- and polyfluoroalkyl substance (PFAS) transport from groundwater to five tributaries of the Cape Fear River near a PFAS manufg. facility in North Carolina (USA). Hydrol. and PFAS data were coupled to quantify PFAS fluxes from groundwater to the tributaries. Up to 29 PFAS were analyzed, including perfluoroalkyl acids and recently identified fluoroethers. Total quantified PFAS (ΣPFAS) in groundwater was 20-4773 ng/L (mean = 1863 ng/L); the range for stream water was 426-3617 ng/L (mean = 1717 ng/L). Eight PFAS constituted 98% of ΣPFAS; perfluoro-2-(perfluoromethoxy)propanoic acid (PMPA) and hexafluoropropylene oxide dimer acid (GenX) accounted for 61%. For PFAS discharge from groundwater to one tributary, values estd. from stream water measurements (18 ± 4 kg/yr) were similar to those from groundwater measurements in streambeds (22-25 ± 5 kg/yr). At baseflow, 32 ± 7 kg/yr of PFAS discharged from groundwater to the five tributaries, eventually reaching the Cape Fear River. Given the PFAS emission timeline at the site, groundwater data suggest the abundant fluoroethers moved through the subsurface to streams in «50 yr. Discharge of contaminated groundwater may lead to long-term contamination of surface water and impacts on downstream drinking water supplies. This work addresses a gap in the PFAS literature: quantifying PFAS mass transfer between groundwater and surface water using field data.
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    • Video of PILSNER collection (ZIP)

    • Calculations of aerosol counts, diffusion times, and aerosol volumes; ferrocyanide cyclic voltammograms; aerosol histograms; overlaid anodic stripping voltammograms; images of collector droplet; humidity-based amperometric response curve; statistical analyses; PFOS DPV initial currents; non-normalized PFOS DPV response; and amperometric controls (PDF)


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