1 An efficient method for measuring dissolved VOSCs in wastewater 1

Abstract 15 Volatile organic sulfur compounds (VOSCs) are important sources of unpleasant odor 16 in wastewater systems. However, the study of VOSCs is usually hindered by their 17 complicated measurement method and highly reactive nature. In this work, a static 18 headspace method utilising gas chromatography (GC) with a sulfur 19 chemiluminescence detector (SCD) was developed to quantitatively analyze VOSCs 20 in wastewater matrices. The method has low detection limits and requires no pre-21 concentration treatment. Three typical VOSCs, namely methanethiol (MT), dimethyl 22 sulfide (DMS) and dimethyl disulfide (DMDS), were chosen as examples for this 23 study. The calibration curves of all three compounds covering a wide range from 0.5 24 ppb to 500 ppb showed good linearity (R2>0.999). The method detection limits (MDL) 25 were 0.08, 0.12 and 0.21 ppb for MT, DMS and DMDS, respectively. The 26 reproducibility (relative standard deviation) was approximately 2%. The recovery 27 ratio of MT, DMS and DMDS in spiked wastewater samples were 83±4%, 103±4 % 28 2 and 102±3%, respectively. Sample preservation tests showed that VOSCs in 29 wastewater samples could be preserved in vials without headspace under acidified 30 conditions (pH ~1.1) for at least 24 h without significant changes (<1.8 ppb). The 31 analysis of real wastewater samples from both a laboratory-scale sewer system and a 32 full-scale sewer pipe demonstrated the suitability of this method for routine 33 wastewater VOSC measurement. 3