In:
Rapid Communications in Mass Spectrometry, Wiley, Vol. 36, No. 1 ( 2022-01-15)
Abstract:
The identification of V‐type nerve agents poses an analytical challenge. Their spectra obtained by electron ionization mass spectrometry (EI‐MS) and electrospray ionization tandem mass spectrometry (ESI‐MS/MS) are dominated by ions originating from the N,N ‐dialkylaminoethyl moiety, while ions representative of the alkyl phosphonothiolate part are absent from the spectra or present at negligible abundance. Hence, analogs or isomers with the same amine residue exhibit similar mass spectral patterns, leading to unavoidable ambiguity in their identification. Methods Chemical derivatization was utilized for the structural elucidation of a series of five V‐type nerve agents, including O ‐ethyl S ‐(2‐diisopropylamino)ethyl methylalkyl phosphonothiolate (VX), O ‐isobutyl S ‐(2‐diethylamino)ethyl methylalkyl phosphonothiolate (RVX) and O ‐ethyl S ‐(2‐diethylamino)ethyl methylalkyl phosphonothiolate (VM). The procedure consisted of “in‐vial” oxidation of the tertiary amine group with 3‐chloroperbenzoic acid ( m ‐CPBA) at ambient temperature followed by liquid chromatography (LC)/Orbitrap‐ESI‐MS/MS analysis with no other sample preparation. Results The generated N‐oxide of the V‐type nerve agents altered the charge distribution occurring during fragmentation and produced informative ESI‐MS/MS spectra characteristic of the alkyl phosphonothiolate structure, enabling a higher degree of certainty in their identification. Moreover, two VX isomers possessing an identical tertiary amine moiety that coeluted at practically the same retention time and displayed high mass spectral similarity were easily differentiated, and their structures elucidated once derivatized. Conclusions In contrast to the ESI‐MS/MS spectra of the V‐type nerve agents, which exhibited mostly/only information on the amine‐containing residue, the ESI‐MS/MS spectra of the V‐type nerve agent N‐oxides revealed ions indicative of both the alkyl phosphonothiolate and the amine parts, enabling their reliable structural elucidation.
Type of Medium:
Online Resource
ISSN:
0951-4198
,
1097-0231
Language:
English
Publisher:
Wiley
Publication Date:
2022
detail.hit.zdb_id:
2002158-6
detail.hit.zdb_id:
58731-X
SSG:
11
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