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ABSTRACT: A simple but reliable procedure was developed to analyze dimethyl sulfoxide (DMSO) in wastewater. The isotope DMSO_d6 was used as the internal standard to ensure accuracy. The DMSO was reduced with stannous chloride and measured as dimethyl sulfide (DMS) with purge-and-trap gas chromatography/mass spectrometry. The method detection limit was at the sub-microgram-per-milliliter level; precision, as measured by standard deviation, was better than ±0.5%; and the recoveries were between 95 and 105% at the level of 2 µg/mL. The procedure could use standard analytical instrumentation used for volatile organic compound analysis. A field study was conducted to validate the method and quantify DMSO concentration range in the three water pollution control plants (WPCPs) in the city of Philadelphia, Pennsylvania. Results showed that, when a local chemical facility discharged, DMSO concentration could be as high as 12 mg/L in the influent to a WPCP. This would lead to the formation of a toxic "canned corn" DMS odor during the treatment processes. Water Environ. Res., 79, 571 (2007).
KEYWORDS: dimethyl sulfoxide, DMSO, DMS, wastewater.
doi:10.2175/106143006X123094
Introduction
Dimethyl sulfoxide (DMSO), commercially produced by the oxidation of dimethyl sulfide (DMS), is largely used as an industrial solvent. It is also a natural component in food and beverages and has been observed in natural environments (Pearson et al., 1981; Sciare et al., 1998). Because of its potential use for pharmaceuticals and the role it may play in regulating climate, it has been studied intensively in these fields (i.e., Lonobro and Wadso, 1991; Sciare and Mihalopoulas, 2000).
The analytical methods for DMSO were summarized by Ashworth (1972) and Simo (1998). For quantitative analysis of DMSO at trace level, reduction with reducing agents and subsequent analysis as DMS appeared to be the technique of choice. However, achieving satisfactory reproducibility with this technique proved to be a challenge, because the reduction yields were highly dependent on operating conditions. Application of isotope-dilution gas chromatography/mass spectrometry (GC/MS), in which perdeuterated DMSO was added as an internal standard, resolved the issue because the DMSO concentration was calculated by the ratio of hexadeutero DMS/DMS ([2H6]DMSTDMS) (Ridgeway et al., 1992). However, most of these methods that analyze DMSO as DMS require cryogenic equipment, which has a higher cost but lower throughput, and need method-specific instrumentation.
Because DMSO...