Poison Analysis of Organophosphorus Pesticides by LC-MS/MS

OBJECTIVE To establish a liquid chromatography/tandem mass spectrometry method(LC-MS/MS) to simultaneously determine nine organophosphorus pesticides in human plasma. METHODS The analytes were chromatographed on a Thermo C₁₈ (4.6 mm×250 mm, 5 μm) column at 25 ℃. The mobile phase was consisted of acetonitrile and water including 20 mmol·L^-1 ammonium acetate and 0.1% formic acid (85∶15) with a flow rate of 0.3 mL·min^-1. The plasma samples were precipitated by acetonitrile. LC-MS/MS detection was made with an electrospray positive ionization and multiple reaction monitoring. RESULTS The calibration curves of each organophosphorus pesticide showed a good linearity in a range of concentration between 0.05-10 μg·mL^-1. Lower limit of quantitation was 0.05 μg·mL^-1 and the limits of detection were ranged from 0.1 to 5 ng·mL^-1. The recoveries were between 93.23% and 107.5%. The intra- and inter- batch precisions were less than 10% and the stability was good. CONCLUSION The method is proved to be accurate, sensitive, simple and fast. It can be used to screen and determine the organophosphorus pesticides in patients, which can effectively support the diagnosis and efficacy evaluation of poisoned patients in clinical practice.