Verification of Lewisite Exposure: Quantification of Chlorovinylarsonous Acid in Biological Samples.

Lewisite dichloro-2-chlorovinylarsine is a chemical warfare vesicant which causes immediate pain and systemic arsenic poisoning. Under alkaline conditions, lewisite is rapidly converted to acetylene, chloride ion, and arsenic trioxide. These products can be monitored but are not necessarily specific for lewisites. In our opinion, a better marker of exposure can be found in lewisites acidic hydrolysis products which are chlorovinyl arsonous acid CVAA and HC1. CVAA preserves most of lewisites structure and retains vesicant properties. There are major analytical problems with direct CVAA analysis because of its limited volatility and aqueous solubility. However, CVAA can be made volatile by derivatizing with 1,2-ethanedithiol EDT. The derivative, 2-2-chlorovinyl-1,3,2-dithiarsenoline, is rapidly formed using a three-fold molar excess of EDT and is relatively stable. Results indicated that CVAA can be derivatized directly in spiked urine or serum. Urine and serum samples spiked with CVAA and extracted with toluene were analyzed by gas chromatography-electron ionization mass spectrometry in the selected ion monitoring mode using phenylarsine oxide as the internal standard. Results indicated a linear relationship between the peak area ratio and concentration from 4000 to 20 ngmL.