A Simple Colorimetric Detector of Symmetric 2-(Dialkylamino)ethanethiols as Precursors of v-Type Nerve Agents

Abstract

A colorimetric detector tube of 2-(dialkylamino)ethanethiols as precursors of V-type nerve agents and their hydrolytic products was designed. The detector is based on a reaction of 2-(dialkylamino)ethanethiols with a chromogenic reagent 4-chloro-7-nitrobenzofurazan (NBD-Cl) in alkaline medium leading to characteristic coloured products. The detection limit in water is of 5 μg/ml, the optimum measurement range being up to 250 μg/ml. The detector also presented a response to some other warfare chemical agents, the colour shade being, however, different. Effects of disturbing substances and organic solvents were studied.

Simple Chemical and Cholinesterase Methods for the Detection of Nerve Agents Using Optical Evaluation

“…The presence of 2-dialkylaminoethanethiols as hydrolytic products distinguishes the V-series compounds (VX, R-33, and others) from all other types of organophosphorus CWAs. In military practice, the ability of these hydrolytic products to reduce and thereby decolourize certain triphenylmethane dyes such as Malachite Green or Guinea Green [17], to reduce Ellman's reagent to give a yellow-coloured product [18,19], Folin-Ciocalteu's reagent [20] to give a green product, or 4-chloro-7-nitrobenzofurazan [21] to give similarly coloured compounds, has been exploited. Also of interest is the ability to detect thiol hydrolysis products using a specific fluorogenic reagent based on fluorescein [22].…”

“…Biosensors 2023, 13, x FOR PEER REVIEW 5 of 18 reagent [20] to give a green product, or 4-chloro-7-nitrobenzofurazan [21] to give similarly coloured compounds, has been exploited. Also of interest is the ability to detect thiol hydrolysis products using a specific fluorogenic reagent based on fluorescein [22].…”