Determination of Glufosinate-Ammonium and Its Metabolite 3-Methylphosphinico-Propionic Acid in Blood by High Performance Liquid Chromatography- Tandem Mass Spectrometry

Two heart blood samples of poisoning decedents caused by oral glufosinate-ammonium were used to analyze the presence of glufosinate-ammonium metabolites in human body, and it was determined that the detection targets in blood of poisoning deceden caused by glufosinate-ammonium were glufosinate-ammonium and its main metabolite 3-methylphosphinico-propionic acid, and a method for the determination of glufosinate-ammonium and its metabolite 3-methylphosphinico-propionic acid in blood by high performance liquid chromatography-tandem mass spectrometry was proposed. The protein was precipitated under the condition of blood, water and acetonitrile at volume ratio of 1∶0.5∶3, and the obtained supernatant was mixed with dichloromethane with the same volume as acetonitrile. After vortex and centrifugation, the upper water phase was filtered by 0.22 μm water phase filter membrane, and the resulting filtrate was injected into high performance liquid chromatograph. Gradient elution was performed on a cheap Dikma Polyamino HILIC column (150 mm×2.0 mm, 5 μm) as stationary phase, with 1.25% (volume fraction) ammonia solution containing 5 mmol·L^-1 ammonium acetate-acetonitrile as mobile phase system. The separated targets were scanned by electrospray ion source with negative ion mode, and detected by multi-reaction monitoring mode, with matrix matching method for quantification. As shown by the results, the linear ranges of the working curves for glufosinate-ammonium and 3-methylphosphinico-propionic acid were 0.2-10.0 mg·L^-1, with detection limits (3S/N) of 0.1 mg·L^-1. Test for recovery was made on the blank heart blood at 3 concentration levels by standard addition method, giving results of glufosinate-ammonium and 3-methylphosphinico-propionic acid in the ranges of 35.6%-50.1% and 50.6%-70.1%, respectively,with intra-day precision (n=6) in the ranges of 5.7%-8.7% and 6.9%-8.9%, respectively, and inter-day precision (n=6) in the ranges of 5.7%-6.3% and 4.2%-9.6%, respectively. The two blood samples from actual cases were quantitatively analyzed, in which the mass concentrations of glufosinate-ammonium were 5.8 mg·L^-1 and 7.5 mg·L^-1, and the mass concentrations of metabolite 3-methylphosphinico-propionic acid were 5.3 mg·L^-1 and 5.8 mg·L^-1.