Determination of the main hydrolysis product of O-ethyl S-2-diisopropylaminoethyl methylphosphonothiolate, ethyl methylphosphonic acid, in human serum.
For the unequivocal proof of the use of a nerve agent O-ethyl S-2-diisopropylaminoethyl methylphosphonothiolate (VX), a rapid, accurate and sensitive method which allows us to identify its main hydrolysis product ethyl methylphosphonic acid (EMPA) in human serum was explored by GC-MS. GC-MS analysis was performed after solvent extraction with acetonitrile in acidic conditions from the serum sample, which was previously deproteinized by micro-ultrafiltration, and subsequent tert.-butyldimethylsilyl derivatization with N-methyl-N-(tert.-butyldimethylsilyl)trifluoroacetamide (MTBSTFA) with 1% tert.-butyldimethylsilyl chloride (t-BDMSC). Linear calibration curves were obtained in the concentration range from 50 to 500 ng/ml for EMPA in the full-scan EI mode and from 5 to 50 ng/ml for EMPA in the SIM EI mode. The relative standard deviation obtained at a sample concentration of 50 ng/ml was 8.4% in the full-scan mode and 7.3% in the SIM mode. Upon applying the full-scan EI and CI mode, 40 ng/ml and 80 ng/ml were the detection limits. Using the SIM-EI mode, in which the ion at m/z 153 was chosen, the limit was 3 ng/ml.
Katagi
M
M
Forensic Science Laboratory, Osaka Prefectural Police H.Q., Japan.
Nishikawa
M
M
Tatsuno
M
M
Tsuchihashi
H
H
D002800:Cholinesterase Inhibitors / Q000097:blood*; D008401:Gas Chromatography-Mass Spectrometry / Q000379:methods*; D006801:Humans; D006868:Hydrolysis; D007202:Indicators and Reagents / Q000737:chemistry; D009943:Organophosphorus Compounds / Q000097:blood*; D017646:Organosilicon Compounds / Q000737:chemistry; D009946:Organothiophosphorus Compounds / Q000097:blood*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
D002800:Cholinesterase Inhibitors; D007202:Indicators and Reagents; D009943:Organophosphorus Compounds; D017646:Organosilicon Compounds; D009946:Organothiophosphorus Compounds; C009660:t-butyldimethylsilyl compounds; C032627:methylphosphonic acid; C009680:VX-agent