Investigating the variation of thermal conductivity with temperature to improve a portable gas chromatography (GC) system's specificity

Abstract. In the context of field thermal conductivity detector (TCD)-based gas chromatography (GC), we investigate a method to improve the system's specificity. The ratio of signals of two TCDs biased at two different voltages is calculated, allowing us to be independent of the analyte concentration and to exploit the fact that the thermal conductivity of any gaseous species varies uniquely with temperature. However, theoretical predictions as well as experiments indicate that this method helps peak identification only if the local analyte concentrations are far (2 to 3 orders of magnitude) beyond the typical concentrations encountered by portable trace analyzers.