LC/MSによる生体試料中のマラチオン代謝物の分析  [in Japanese] Determination of Malathion Metabolites in Biological Samples by LC/MS  [in Japanese]

The procedure for the determination of the main metabolites of malathion (MA), malaoxon (MO), malathion dicarboxylic acid (DCA), malathion α-, β-monocarboxylic acid (α-, β-MCA), desmethyl malathion (DM-MA), in addition to unchanged MA was investigated using positive-ion mode thermospray liquid chromatography-mass spectrometry (TSP-LC/MS). Following the solid-phase extraction of the sample at pH 2 using Sep-Pak C_<18> cartridge with methanol as eluent, the extract was analyzed on TSP-LC/MS. LC analyses were performed on C_<18>-bonded phase using methanol-100 mM ammonium acetate (60 : 40 v/v, pH 3.65 with trifluoro acetic acid) as eluent at a flow rate of 1.0 ml/min. Every mass spectrum of MA and its metabolites provided both the protonated molecular ion [M+H]^+ and the ammonium adduct ion [M+NH_4]^+. By the solid-phase extraction, they were recovered relatively well, and the detection limits were ranged from 0.2 μg/ml to 2.5 μg/ml by scan mode, ranged from 5 ng/ml to 200 ng/ml by selected ion monitering (SIM) mode. In the urine sample, the coefficients of variations for the prepared method by SIM mode were ranged from 3.3% to 7.2% at 500 ng/ml level of each metabolite. For a blood sample of a female, who had committed suicide by taking MA, TSP-LC/MS analysis were attemped following the prepared method, the metabolites such as α-MCA were detected, and it was possible to prove that she had taken MA.