Optimized Gas Chromatography-Tandem Mass Spectrometry for 1,1'-sulfonylbis[2-(methylthio) ethane] Quantification in Human Urine.

Sulfur mustard (SM) which is a bifunctional alkylating vesicant is one of the mostly used chemical warfare agent in First World War and the Iran-Iraq War. β-Lyase metabolites of SM especially 1,1'-sulfonylbis[2-(methylthio)ethane] (SBMTE) is an unequivocal biomarker of the exposure. An optimized gas chromatography-tandem mass spectrometry method was developed and validated for the retrospective detection of SBMTE in human urine. Urine samples were treated with acidic titanium trichloride to reduce β-lyase metabolites to the single analyte SBMTE. After neutralization and precipitation, SBMTE was extracted from urine by C8 solid-phase extraction cartridge and analyzed in the multiple-reaction monitoring mode. The lower limit of quantification was 1 ng/mL with relative standard deviation of <10%. Acceptable intra-day and inter-day precisions and accuracies were obtained. The developed method was successfully measured various levels of SBMTE which could be used as the forensic evidence of such a chemical attack.