Performance characterization of the GC/PFPD for H2S, CH3SH, DMS, and DMDS in air

In an effort to provide detailed information concerning the analysis of reduced S compounds, we carefully examined the response properties of four different compounds (H2S, CH3SH, DMS, and DMDS) using the GC/PFPD system. Such properties were assessed mainly in terms of both absolute detectability in mass (or concentration) and relative calibration patterns across different S gases. The results of our analysis, when inspected in terms of calibration data over a wide concentration range, indicated that the patterns could be affected greatly by the absolute content of S analyzed with notable differences among different S compounds. The causes of such differences appeared to be associated with different processes (or mechanisms) such as either some type of (adsorptive) loss within the system (H2S) or moderate variabilities in linearity (DMS and DMDS). Relative response factors (RRF) of these S gases, when computed by their calibration slope values through normalization of the least variable results (CH3SH), were found to increase in the order of H2S, CH3SH, DMS, and DMDS. The DL values of all S gases for our analytical system were typically estimated in a few pg or a few ppb range (e.g., at 500 μl sample volume) with considerable differences in their linearity responses.