Determination of diphenylarsenic compounds related to abandoned chemical warfare agents in environmental samples

To elucidate the current extent of pollution of the environment with diphenylarsine chloride (DA, Clark I) and diphenylarsine cyanide (DC, Clark II), we have developed analytical procedures using gas and liquid chromatography and employed them to analyze water and soil samples. DA, DC, and their degradation products were extracted with water or organic solvents. Derivatization with n-propanethiol was adopted to achieve higher analytical reproducibility. DA and DC were unstable and decomposed into bis(diphenylarsine)oxide (BDPAO) in water, but only negligibly into diphenylarsinic acid (DPAA) during the 30 days of a stability test. Diphenylarsenic compounds afforded the same product by this derivatization, but their reaction rates varied depending on the starting materials. DPAA had to be treated under acidic conditions at 60 °C to achieve the desired conversion efficiency. Recovery of the thiol derivatives of the diphenylarsenic compounds tested was almost quantitative from water, but only about 50% from soil, reflecting the low extraction efficiency. We applied the method to the analysis of organoarsenic compounds sampled from the water of the drinking well in Kamisu-cho, Ibaraki Prefecture, where the water was thought to have had deleterious effects on the inhabitants. The high level of DPAA was identified as the causative agent. Our analyses of soil samples from Samukawa-cho and Hiratsuka City, Kanagawa Prefecture, where a naval arsenal had previously stood, succeeded in identifying intact DA, BDPAO and triphenylarsine, diphenylarsenic thiol-derivatives, as well as other substances (mustard gas, lewisite). The true magnitude of contamination became evident after these measurements. Copyright © 2005 John Wiley & Sons, Ltd.