BIOANALYSIS OF ORGANOPHOSPHATE NERVE AGENTS IN SOIL SAMPLES

Four soil samples that may have been spiked with chemical warfare (CW) agents and their degradation products were received by Defence Resear ch Establishment Suffield as part of a multinational round-robin exerc ise designed to evaluate laboratory methodologies for the chemical det ection of CW agents in soil. After chemical analysis revealed that VX (ethyl S-2-diisopropyl aminoethyl methylphosphorothiolate) was the CW agent ''spike'', the samples were also bioassayed for their VX content by assessing their anticholinesterase activities in primary chick emb ryo neuron cultures. Bioassay quantitation of VX contamination in the soil samples was in good agreement with the actual spike levels and ge nerally better than the chemical analytical results. Sequential bioass ay of the samples over a two week period showed that the VX content wa s rapidly degraded with time. This assay complements standard chemical analytical techniques for the detection and verification of organopho sphate warfare agent use.