Detection of 2-(Dialkylamino)ethanethiols and v-Series Nerve Agents in Water and Aqueous Solutions Using Folin-Ciocalteu Reagent

Abstract

SummaryA simple colorimetric tube detector for the detection of 2-(dialkylamino)ethanethiols and V-series nerve agents in water and in aqueous solutions is proposed. The detector is based on the reaction of the compounds with a chromogenic Folin-Ciocalteu reagent yielding a blue coloured reduction product. The detection limit of 2-(dialkylamino)ethanethiols is 2.5 mg/l, measurement range up to 250 mg/l. The detection limit of the V (VX) agent is 10 mg/l. The method allows V agents and their precursors and hydrolysis products to be easily distinguished from G-series nerve agents.

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].…”

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

“…The monitoring process also includes their chemical analysis taking advantage of a variety of instrumental methods as well as relatively simple procedures, including methods based on reducing effects accompanied by colour changes 5 . For the detection and determination of 2-(dialkylamino)ethanethiols and structurally similar substances, it is for example possible to use their reactions with iodine, potassium permanganate, 4,4'-bis(dimethylamino)benzophenone oximes, quinone oximes, tetrazolium compounds (triphenyltetrazolium chloride, Tetrazolium Blue) 6 , Folin-Ciocalteu reagent 7 or with further reagents 8,9 . The obviously most frequently used approach is a classical method based on the reduction of the Ellman reagent or its analogues leading to colour products [10][11][12] .…”