Determination of glufosinate ammonium and three metabolites in urine by ultra performance liquid chromatography-tandem mass spectrometry

Backgroud At present, there is no unified standard for the detection of glufosinate ammonium and three metabolites in urine, which affects the accurate assessment of occupational exposure risk to a certain extent. It is of great significance to establish a rapid and effective inspection method to ensure occupational safety and public health.

Objective To establish an ultra performance liquid chromatography-tandem mass spectrometry for simultaneous determination of glufosinate ammonium and three metabolites in urine.

Methods The effects of dilution solvents and dilution ratios on the response values of glufosinate ammonium and three metabolites were compared, and the retention capacities of solid phase extraction columns for targets as well as the effects of chromatographic columns and mobile phase systems on chromatographic peaks were analyzed. Samples were quantified by matrix effect matching external standard method. Accuracy of the method was evaluated by recovery rate of standard addition, and precision of the method was evaluated by relative standard deviation of intra-day and inter-day measurements. Urine samples of 30 health individuals were collected to evaluate the application of the method.

Results The urine samples were diluted with 0.2 mL water and 0.6 mL acetonitrile, purified by HLB solid phase extraction columns, and separated by Dikma Polyamino HILIC columns, and gradient elution was carried out with 0.5 mmol·L⁻¹ ammonium acetate and 0.1% ammonia water as mobile phase, which achieved a good peak shape and mass spectrum response. The linearities of the four target compounds were good in the range of 0.5-50 ng·mL⁻¹, and the correlation coefficients (r) were all greater than 0.998. The detection limits were 0.56-2.86 μg·L⁻¹, the quantification limits were 1.87-29.54 μg·L⁻¹, and the recovery rates of standard addition ranged from 75.0% to 103.6%, The relative standard deviations of intra-batch and inter-batch were from 2.5% to 8.1% and from 4.3% to 9.3% respectively. The method was applied to detect 30 urine samples of subjects, and no target was detected.

Conclusion The method is simple, rapid, sensitive, and accurate. It is suitable for the determination of glufosinate ammonium and its metabolites in human urine without derivatization.