Thermal conductivity detector analysis of hydrogen using helium carrier gas and HayeSep® D columns

The thermal conductivity detector (TCD) response of hydrogen using helium carrier gas is investigated to obtain a linear response in the 6-60% hydrogen concentration range. The study is conducted using a Hewlett-Packard 5890 Series II GC incorporating either one or two 1.83-m x 3.18-mm stainless steel columns packed with 80/100-mesh HayeSep® D. Replicate data are analyzed using an analysis of variance (ANOVA) for testing the linearity of regression. TCD response curves are generated for replicates of three sets of sample size and TCD temperature: 10 μL and 130°C, 1 mL and 300°C, and 100 μL and 140°C. The linearity is limited: 6-32.5% hydrogen and 32.5-66.9% hydrogen for 10 μL, 6-50.3% hydrogen for 1 ml, and nonlinear for 100 μL (0.82-8.7% hydrogen). These results are in sharp contrast to those of Villalobos and Nuss (1965), who report a linear response from 0 to 70% hydrogen with a 50-μL sample. The nonlinear response observed in the present study is hypothesized to be due to better resolution obtained with the HayeSep D columns, producing taller peaks. Consequently, for a given sample size, the maximum concentration in the Gaussian peak surpasses the linear range of the hydrogen-in-helium TCD response, yielding concave-downward curves for small sample sizes.