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An Inexpensive Detector for Gas Chromatography

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Wolfgang Nadler

College of Arts & Sciences, Drexel University, Philadelphia, PA 19104

Allan L. Smith and Edward J. Thorne

Department of Chemistry, College of Arts & Sciences, Drexel University, Philadelphia, PA 19104

J. Chem. Educ., 1998, 75 (9), p 1129

DOI: 10.1021/ed075p1129

Publication Date (Web): September 1, 1998

Abstract

We have developed a low-cost (parts cost approximately $70) detector that can be used in a freshman level class to demonstrate the fundamental principles of gas chromatography (GC). The detector box can be used in a modification of experiments available in the literature which do not enable a quantitative method of analysis. We have used it with success in a freshman class of approximately 450 students in an experiment to separate chlorinated hydrocarbons via GC. Natural gas is used as the carrier gas, a commercial GC column packing is the separating medium, and a Beilstein detector generates a green flame when the halocarbon is burned as it exits the column. The detector box is equipped with a CdS detector selective for the green light emitted and gives a signal that is quantitatively measured by an appropriate means such as a strip chart recorder or computer interfaced terminal panel.The detector box has a limit of detection on the order of 0.5 to 5 mg and shows a linear response over a sixfold change in concentration. Very small volumes (only about 0.1 ml) of most halocarbon vapors are necessary to achieve a measurable signal.