Determination of trace amounts of G-type nerve agents in aqueous samples utilizing "in vial" instantaneous derivatization and liquid chromatography-tandem mass spectrometry.

A methodology for sensitive determination of sarin (GB), soman (GD) and cyclosarin (GF) chemical warfare agents in aqueous media was developed. The method incorporates direct derivatization with 2-[(dimethylamino)methyl]phenol (2-DMAMP), a commercially available, water-soluble reagent, followed by LC-ESI-MS/MS analysis in the positive ion mode. Five derivatization agents were characterized for their MS/MS fragmentation pattern, and their reaction time, temperature and derivatization-reagent amount were optimized. The developed derivatization reaction is simple, fast (1min) and proceeds at ambient temperature. Sample preparation consists of only the addition of the reagent directly into an injection vial prior to LC-ESI(+)-MS/MS analysis. All 2-DMAMP derivatives were stable for at least 48h and had unique tandem mass spectra characterized by common product ions at m/z 230 and 185. Compared with conventional GC-MS or LC-MS methods, simplicity, better sensitivity and informative MS/MS spectra were achieved by this method. Limits of detection (LODs), identification (LOIs), and quantification (LOQs) were determined in tap water and found to be 1pg/ml, 4pg/ml and 4pg/ml respectively. The proposed methodology is appropriate for routine evaluation of contaminated water supplies and has the advantage of a simultaneous analysis of both derivatized G-nerve agents and their intact hydrolysis products within a single LC-MS analysis.