Pitfalls in the Detection of Volatiles Associated with Heated Tobacco and e-Vapor Products When Using PTR-TOF-MS

We investigated the applicability of proton transfer reaction-time-of-flight mass spectrometry (PTR-TOF-MS) for quantitative analysis of mixtures comprising glycerin, acetol, glycidol, acetaldehyde, acetone, and propylene glycol. While PTR-TOF-MS offers real-time simultaneous determination, the method selectivity is limited when analyzing compounds with identical elemental compositions or when labile compounds present in the mixture produce fragments that generate overlapping ions with other matrix components. In this study, we observed significant fragmentation of glycerin, acetol, glycidol, and propylene glycol during protonation via hydronium ions (H3O+). Nevertheless, specific ions generated by glycerin (m/z 93.055) and propylene glycol (m/z 77.060) enabled their selective detection. To thoroughly investigate the selectivity of the method, various mixtures containing both isotope-labeled and unlabeled compounds were utilized. The experimental findings demonstrated that when samples contained high levels of glycerin, it was not feasible to perform time-resolved analysis in H3O+ mode for acetaldehyde, acetol, and glycidol. To overcome the observed selectivity limitations associated with the H3O+ reagent ions, alternative ionization modes were investigated. The ammonium ion mode proved appropriate for analyzing propylene glycol (m/z 94.086) and acetone (m/z 76.076) mixtures. Concerning the nitric oxide mode, specific m/z were identified for acetaldehyde (m/z 43.018), acetone (m/z 88.039), glycidol (m/z 73.028), and propylene glycol (m/z 75.044). It was concluded that considering the presence of multiple product ions and the potential influence of other compounds, it is crucial to conduct a thorough selectivity assessment when employing PTR-TOF-MS as the sole method for analyzing compounds in complex matrices of unknown composition.


Table S9. Ratio between concentration of glycerin to sum of concentrations of acetol and glycidol
1 Data for a model heated tobacco product. 2 The term "stick" is used in the context of heated tobacco products.It refers to the consumable part of such products.The aerosol resulting from consumption of one stick typically corresponds to 12 puffs accumulated.The term "puff" refers to a certain volume of mainstream aerosol collected under standardized conditions (55 mL volume, 3 sec puff duration). 3Volume of 0.5 L. 4 Inhaled: estimated concentrations of inhaled aerosol of one puff of mainstream aerosol of a model product.Exhaled: estimated concentrations of exhaled gas at either 50% or 90% retention in the respiratory tract.

Figure S1 .
Figure S1.Calibration plot of response (cps) versus concentration (ppbV) for acetaldehyde in the H 3 O + mode (E/N 69 Td).NB: a second injection was performed mid-range for quality control purposes to verify the consistency of response.

Figure S2 .
Figure S2.Calibration plot of response (cps) versus concentration (ppbV) for glycerin in H 3 O + mode (E/N 69 Td).NB: a second injection was performed mid-range for quality control purposes to verify the consistency of response.

Figure S3 .
Figure S3.Calibration plot of response (cps) versus concentration (ppbV) for acetol in H 3 O + mode (E/N 69 Td).NB: a second injection was performed mid-range for quality control purposes to verify the consistency of response.

Figure S4 .
Figure S4.Calibration plot of response (cps) versus concentration (ppbV) for glycidol in H 3 O + mode (E/N 69 Td).NB: a second injection was performed mid-range for quality control purposes to verify the consistency of response.

Figure S6 .
Figure S6.Calibration plot of response (cps) versus concentration (ppbV) for acetaldehyde in NO + mode (E/N 16 Td).NB: a second injection was performed mid-range for quality control purposes to verify the consistency of response.

Figure S7 .
Figure S7.Calibration plot of response (cps) versus concentration (ppbV) for glycerin in NO + mode (E/N 16 Td).NB: a second injection was performed mid-range for quality control purposes to verify the consistency of response.

Figure S8 .
Figure S8.Calibration plot of response (cps) versus concentration (ppbV) for acetol in NO + mode (E/N 16 Td).NB: a second injection was performed mid-range for quality control purposes to verify the consistency of response.

Figure S9 .
Figure S9.Calibration plot of response (cps) versus concentration (ppbV) for glycidol in NO + mode (E/N 16 Td).NB: a second injection was performed mid-range for quality control purposes to verify the consistency of response.

Figure S10 .
Figure S10.Calibration plot of response (cps) versus concentration (ppbV) for acetone in H 3 O + mode (E/N 69 Td).NB: a second injection was performed mid-range for quality control purposes to verify the consistency of response.

Figure S11 .
Figure S11.Calibration plot of response (cps) versus concentration (ppbV) for propylene glycol in H 3 O + mode (E/N 69 Td).NB: a second injection was performed mid-range for quality control purposes to verify the consistency of response.

Figure S12 .
Figure S12.Calibration plot of response (cps) versus concentration (ppbV) for acetone in NO + mode (E/N 16 Td).NB: a second injection was performed mid-range for quality control purposes to verify the consistency of response.

Figure S13 .
Figure S13.Calibration plot of response (cps) versus concentration (ppbV) for propylene glycol in NO + (E/N 16 Td).NB: a second injection was performed mid-range for quality control purposes to verify the consistency of response.

Figure S14 .
Figure S14.Calibration plot of response (cps) versus concentration (ppbV) for acetone in NH 4 + mode (E/N 36 Td).NB: a second injection was performed mid-range for quality control purposes to verify the consistency of response.

Figure S15 .
Figure S15.Calibration plot of response (cps) versus concentration (ppbV) for propylene glycol in NH 4 + mode (E/N 36 Td).NB: a second injection was performed mid-range for quality control purposes to verify the consistency of response.

Table S3 . Ratio between concentration of glycerin to sum of concentrations of acetaldehyde and glycidol for Mixture 1.
Abbreviations: cps (counts per sec corrected for transmission and multiplier), ppbV (parts per billion by volume).

Table S5 . Ratio between concentration of glycidol to sum of concentrations of glycerin and acetaldehyde for Mixture 1.
(counts per sec corrected for transmission and multiplier), ppbV (parts per billion by volume).

Table S7 . Ratio between concentration of acetaldehyde to sum of concentrations of glycerin and glycidol for Mixture 2.
(counts per sec corrected for transmission and multiplier), ppbV (parts per billion by volume).

Table S8 . Ratio between concentration of glycidol to sum of concentrations of glycerin and acetaldehyde for Mixture 2.
(counts per sec corrected for transmission and multiplier), ppbV (parts per billion by volume).

Table S9 . Ratio between concentration of glycerin to sum of concentrations of acetol and glycidol for Mixture 3.
Abbreviations: cps (counts per sec corrected for transmission and multiplier), ppbV (parts per billion by volume).