Verification of lewisite exposure by the analysis of 2-chlorovinyl arsonous acid in urine

Verification of lewisite (L) exposure aids in the proper medical treatment of personnel who have come into contact with this vesicant. The purpose of this study was to develop a method for the detection of 2-chlorovinyl arson ous acid (CVAA) in the urine of guinea pigs exposed to L. Guineapigs were s ubcutaneously (sc) injected at 500 mu g/kg with L in sesame seed oil. Urine samples were collected and analyzed at 8-h intervals for 40 h. CVAA is the hydrolysis product that retains most oft's structure. Two gas chromatograp hic methods of detection, mass spectrometry (MS) and atomic emission spectr oscopy (AES), were employed to detect CVAA derivatized with ethanedithiol ( EDT). CVAA-EDT was more amenable to gas chromatographic separation than was CVAA. Samples of urine were extracted with C-18 solid-phase cartridges, el uted with methanol, dried, derivatized with EDT, and analyzed. CVAA-EDT was detected at 3-mu g/mL concentrations in 0- to 8-h samples and less than or equal to 100-ng/mL concentrations in 16- to 24-h samples. Results indicate that CVAA can be detected in guinea pig urine up to 24 h after subcutaneou s L exposure using either MS or AES detectors. Demonstration of CVAA in gui nea pig urine following sc injection with L suggests that its presence in h uman urine would prove exposure to L.