Pretreatment method for hypochlorite decon water before GC analysis of HD, VX, and GD.

Active chlorine decontaminants like hypochlorite are used to destroy chemical warfare agents (CWAs) such as HD, VX and GD due to the former's strong oxidation capacity and high nucleophilicity. In this paper, experiments were performed to identify the main factors affecting agent recovery from decon water. Based on the results, a method to recover residual CWAs from hypochlorite decon water before quantitative determination by GC was developed. The results showed that the extraction solvent was a critical determinant of high CWA recovery. Dichloromethane was more suitable than petroleum either, especially for samples containing GD or low residual CWAs. For VX-containing samples, the use of an alkali solution improved VX recovery. Neutralization was also important for a high CWA recovery, especially for samples with low CWA concentrations and/or strong decontaminant reactivity. The use of 15% sodium sulfite as the neutralization solution gave the best results for hypochlorite decon water. When the optimized conditions of simultaneous sodium sulfite neutralization and dichloromethane extraction were used, the recovery of HD, VX and GD in hypochlorite decon water was greater than 85% at a concentration range of 20 mg/L to 10,000 mg/L.