Submitted to: Analytica Chimica Acta
Publication Type: Peer reviewed journal
Publication Acceptance Date: 6/7/2012
Publication Date: 6/17/2012
Citation: Jo, S., Kim, K., Shon, Z., Parker, D.B. 2012. Identification of control parameters for the sulfur gas storability with bag sampling methods. Analytica Chimica Acta. 738:51-58. Interpretive Summary: Sulfur-containing compounds are often emitted from manure sources into the air at animal feeding operations. These sulfur-containing compounds can be malodorous at low concentrations. Air samples containing sulfur compounds are often collected and stored in sample bags prior to analyses. The storage stabilities of five reduced sulfur compounds (hydrogen sulfide, methanethiol, dimethyl sulfide, dimethyl disulfide, and carbon disulfide) and one oxidized sulfur compound (sulfur dioxide) were compared between two different bag materials (polyvinyl fluoride and polyester aluminum) at five initial concentrations ranging from 1 ppb to 10 ppm. The concentrations in the bags were monitored after storage periods of 0, 1, and 3 days. The percent loss of sulfur gases over time was greater for the higher initial concentrations. The reduced sulfur compounds were more stable than the oxidized sulfur compound. The concentration of sulfur dioxide almost disappeared in the polyvinyl fluoride bag after one day. The results of the study confirm that stability of gaseous sulfur species in sampling bags is greatly affected by initial concentration and oxidation status.
Technical Abstract: Air samples containing sulfur compounds are often collected and stored in sample bags prior to analyses. 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, 1,000, 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 (1,000 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 storabilities of oxidized sulfur compound (SO2) were greatly distinguished from 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 and the associated reactivity.