Identification of control parameters for the sulfur gas storability with bag sampling methods

Abstract

Air samples containing sulfur compounds are often collected and stored in sample bags prior to analysis. The storage stability of six gaseous sulfur compounds (H2S, CH3SH, DMS, CS2, DMDS and SO2) was compared between two different bag materials (polyvinyl fluoride (PVF) and polyester aluminum (PEA)) at five initial concentrations (1, 10, 100, 1000, and 10,000 ppb). The response factors (RF) of these samples were determined after storage periods of 0, 1, and 3 days by gas chromatography-pulsed flame photometric detector (GC-PFPD) combined with an air server (AS)/thermal desorber (TD) system. Although concentration reduction occurred more rapidly from samples of the high concentration standards (1000 and 10,000 ppb), such trends were not evident in their low concentration counterparts (1, 10, and 100 ppb). As such, temporal changes in RF values and the associated loss rates of most sulfur gases were greatly affected by their initial concentration levels. Moreover, the storability of oxidized sulfur compound (SO2) was greatly distinguished from that of reduced sulfur compounds (RSCs), as the former almost disappeared in the PVF bag even after one day. The results of our study confirm that storability of gaseous sulfur species is affected interactively by such variables as initial gas concentration level, bag material type, and oxidation status with the associated reactivity. (C) 2012 Elsevier B.V. All rights reserved.