TITLE:
Identification of N-Methyl Bis(2-(Alkyloxy-Alkylphosphoryloxy)Ethyl) Amines by LC-HRMS/MS
AUTHORS:
Huilan Yu, Shilei Liu, Daoming Sun, Chengxin Pei, Yu Xiang
KEYWORDS:
Chemical Weapons, LC-HRMS/MS, N-Methyl Bis(2-(Alkyloxy-Alkylphosphoryloxy)Ethyl)Amines, Fragmentation Pathways, Analysis
JOURNAL NAME:
American Journal of Analytical Chemistry,
Vol.5 No.13,
September
11,
2014
ABSTRACT: N-Methyl bis(2-(alkyloxy-alkylphosphoryloxy)ethyl)amines, which are abbreviated as PNPs, are a series of new
skeleton chemicals belonging to schedule 2.B.04 chemicals of Chemical
Weapons Convention (CWC). PNPs are important markers of chemical
warfare agents because they are structurally relative to both nerve agents and
N-mustards. In this study, fragmentation pathways of
the most characteristic fragment ions in Q-TOF mass spectrometry were proposed
based on the information from accurate mass and secondary fragmentations of
product ions scan experiments. Results indicated that the base ion in LC/HRMS
was the quasi-molecular ion [M+H]+. In LC-HRMS/MS,
it was [M+H-CnH2n+1P(O)(OH)CmH2m+1O]+ fragment ion which was formed by losing an alkyloxy alkylphosphoryloxy
group from the quasi-molecular ion. The diagnostic ion m/z84.0814
was identified as [C5H10N]+, which was the
group of (CH2=CH)2N+(H)CH3.
PNPs have two protonated centers. One is on the N atom, the other is on the O
atom (P=O). O-n-propyl PNPs
generally exhibited two fragmentation pathways. Firstly, the quasi-molecular
ion [M+H]+ lost
a propoxy alkylphosphoryloxy
group to produce [R1P(OH+)(O-n-C3H7)OCH2CH2N(CH3)CH=CH2]+,
which could be fragmented further to produce [C5H10N]+ ion. Secondly, [R1P(OH+)(O-n-C3H7) OCH=CH2]+ ions were produced from [M+H]+ and fragmented further to produce the
abundant ions [R1P(OH+)(OH)OCH =CH2]. However, O-isopropyl PNPs characteristically produced weak
fragment ions [M+H-C3H6]+, which were
presumably formed via loss of CH3CH=CH2 from [M+H]+. Other PNPs showed similar fragmentation pathways as O-n-propyl PNPs. On
the summarization of the MS fragmentation pathways of PNPs, LC-HRMS/MS
quantitative and qualitative methods were
developed and applied to analyze N-Methyl
bis(2-(butoxy-methylphosphoryloxy)ethyl]amine
in high background organic samples. The analytical results had successfully
supported the sample preparation for the 33rd official proficiency
test of Organization for Prohibition of Chemical Weapons (OPCW).