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A procedure was developed for determining traces of O-isopropyl methylphosphonofluoridate (sarin) in soils at a level of 2 × 10−4 mg/kg. The procedure is based on solvent extraction with a hexane-benzene mixture, the preconcentration of the extract to a small volume, the synthesis of dialkyl esters using secondary alcohol aluminates, and gas-chromatographic separation on an HP-1 column with a flame ionization detector. The determination error does not exceed 29%; the time of analysis is 1 h.

The conversion of 2-chlorvinyldichloroarisine ClCH=CHAsCl2 (lewisite, I) in various soil samples is studied by IR spectroscopy. At the initial stage of the process, the rate and character of lewisite conversion are primarily determined by the presence of free surface hydroxyl groups in the sample (which manifest themselves as narrow intense absorption bands at 3700 and 3620 cm−1), being nearly independent of the content of physically adsorbed water (a wide band at 3430 cm−1). In sandy soils, which contain only a small concentration of hydroxyls, if any, lewisite experiences no noticeable decomposition, at least over a period of five days. By contrast, in clayey soils, possessing a high sorbability, the concentration of hydroxyls, highly reactive species, is large enough to completely hydrolyze lewisite into 2-chlorovinylarsonous acid ClCH=CHAs(OH)2 and then 2-chlorovinylarsineoxide ClCH=CHAsO within several hours.

Procedures for the determination of 04sobutyl- S-2-(N,N-diethylamino)ethyl methylphosphonothioate (VX-like compound) and sarin traces in slag at levels of 5 × 10-5 and 1 × 10-2 mg/kg, respectively, were developed. The procedures are based on the extraction of organophosphorus chemical warfare agents from slag, the preconcentration of the extract, and the conversion of the analytes into dialkyl methylphos-phonates with the use of optically active alcohols. In this case, a solution of AgNO3 in 4-methyl-2-pentanol or a sodium alcoholate solution was used for the derivatization of VX or sarin, respectively. The resulting dias-tereomers were determined by gas chromatography with the use of a flame-photometric detector. The analysis time was no longer than 1.2 or 1 h for the VX-like compound or sarin, respectively.

It is shown that 10-chloro-9,10-dihydrophenarsazine and dibenz[b, f][1,4]oxazepine can be determined with the use of indicator tubes containing 4-chloro-5,7-dinitrobenzofurazan and its N-oxide immobilized on silica gel. The conditions for the determination of these substances in air are determined. The following effects are studied: the nature, particle size, and layer thickness of the support; the nature and concentration of the analytical reagent in the chemisorption layer; the rate and time of air aspiration through the indicator tube; and various components of the sample matrix. The limit of visual detection of the toxic substances is 0.05 mg/m3.

Enzyme assay is proposed for improving the selectivity of the determination of an organophosphorus (carbamate) insecticide in the presence of a heavy-metal salt in a sample (exemplified by a model system containing proserine and mercuric bromide). The method involves the use of a substrate–indicator system based on acylthiocholine and Ellman's reagent (or its derivative).