To analyze trace-level, reduced sulfur compounds (RSC) in ambient air, gas chromatography (GC) is used as the commonest method. The GC-based analysis is generally conducted by transferring samples via direct injection into GC or by the combined treatment of cryofocusing (CF) and thermal desorption (TD). In this study, experimental bias involved in GC analysis is examined by evaluating the calibration properties of each transfer approach. To this end, the detection properties of RSCs were evaluated with respect to the two major variables of sample concentration and sample volume. The recovery rate of TD application was also discussed based on the most recent findings in which its recovery rate is compared against the results derived by the direct injection method. The overall results suggest that the TD-based analysis of RSCs can be optimized by unifying the experimental conditions between sample and standard gases.

In order to accurately analyze trace-level, reduced sulfur compounds (RSC) in ambient air, one needs to rely on the thermal desorption technique (TD) to atone for the limited sensitivity of direct gas chromatography (GC) analysis. In this study, the relative performance of GC/PFPD system combined with TD unit was evaluated to help accurately determine RSC based on the comparative analysis of two types of calibration approaches. Hence, calibration results of RSCs were compared by controlling sample transfer system (air server (AS) and TD unit) between the two contrasting calibration approaches such as: incremental-loading of a given standard with the fixed standard concentration (FSC) vs. supply of standards made at multiple concentration points at the fixed standard volume (FSV). The results of our study indicate that RSC calibration is affected fairly sensitively by sample loading conditions of the AS/TD system. It is hence necessary to delicately control the TD operation conditions for the accurate quantification of RSCs, when GC/PFPD system with TD is employed for RSC analysis.