Relative molar response factors for thermal conductivity detectors

This paper describes an investigation into the universal nature of relative molar response factors for thermal conductivity detectors. Relative molar response factors are measured on multiple gas chromatographs equipped with thermal conductivity detectors, and the values are compared with values in the literature. As was observed previously, relative molar responses obtained on a single instrument for a homologous series vary linearly with respect to the number of carbon atoms in the hydrocarbon chain. However, significant differences are observed for the slope of this line depending on the instrument studied. This contradicts previous literature results that demonstrated an indepedence of the relative molar response with regard to the detector. The current results show that the calibration of thermal conductivity detectors using literature values for relative molar response factors could produce significant errors in the concentrations measured by the laboratory chromatograph.