Analysis of Xenon Response by Micro-Thermal Conductivity Detector for Gas Chromatography

Abstract

Xenon concentration is an essential parameter for monitoring radionuclide in the atmosphere in the international monitoring system of comprehensive-nuclear-test-ban-treaty (CTBT). A micro-thermal conductivity detector (μTCD) with single resistance heating element in gas chromatography, a concentration detector for any compound, was connected with capillary column and applied to the determination of xenon concentration. To improve the μTCD measuring ability, xenon responses were investigated under the conditions of swept time of sample in loop, column flow rate, reference flow rate, makeup flow rate, oven temperature and detector temperature. And the equivalent xenon response value (EXRV) was particularly discussed. The results showed that when the column flow rate was set at 1.5 mL min−1, the shortest swept time of 1.0 mL gas sample into column was 0.4 min. The EXRV increases with the increases of column flow rate, but independent of oven temperature. When the flow-rate ratio equaled to 2.3, the maximum of EXRV (0.98 μV s hPa−1) was achieved; when flow-rate ratio was in the range of 2–3, the average of EXRV was 0.97 μV s hPa−1, and relative standard deviation was 1.2%. Therefore, all the flow rates of column, reference and makeup would apparently influence the xenon signals and thus the detector performance would be improved by adjusting these parameters in practice.