Objective To establish a method for the determination of fenthion and its five metabolites (fenthion oxide, fenthion sulfone, fenthion sulfoxide, fenthion oxy-sulfone, and fenthion oxy-sulfoxide) in plasma using ultra-performance liquid chromatography (UPLC).
Methods A volume of 0.50 mL plasma sample was extracted with a mixture of ethyl acetate and acetonitrile (1:1, v/v), evaporated to dryness under nitrogen, and reconstituted with methanol. Separation was performed on an ACQUITY UPLC BEH C18 column using a gradient elution with methanol and formic acid aqueous solution as the mobile phase. Detection was carried out with a diode array detector, with qualitative analysis based on retention time and absorption spectra and quantitative analysis using an external standard method based on peak area.
Results Fenthion and its five metabolites showed good linearity within their respective ranges, with correlation coefficients of 0.999 8 to 0.999 9. The limits of detection were 0.1 to 0.2 mg/L, and the limits of quantification were 0.3 to 0.6 mg/L. The spiked recovery rates ranged from 87.18% to 111.02%. Intra-batch precision ranged from 0.52% to 9.86%, and inter-batch precision ranged from 1.07% to 7.19%. Except for fenthion oxy-sulfone, the plasma samples could be stored at -40℃ for 7 days.
Conclusions This method is accurate, reliable, simple, and practical for the determination of fenthion and its five metabolites in plasma.
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