Establishment of a modified QuEChERS extraction and liquid chromatography-tandem mass spectrometry method for multiple pesticide residues followed by determination of the residue levels and exposure assessment in livestock urine

The establishment of an analytical method for pesticide residues in livestock urine can realize the real-time monitoring of pesticide pollution in livestock breeding. In this study, a novel method was developed for the determination of 106 pesticide residues in livestock urine based on a modified QuEChERS extraction and liquid chromatography-tandem mass spectrometry. Acetonitrile was used to extract target analytes through acidic and alkaline switching of the sample environment. The purification effect of captiva EMR-Lipid on samples was investigated. Three kinds of materials, C18, polar enhanced polymer (PEP), N-propylethylenediamine (PSA), were selected from 20 kinds of materials as adsorbents for QuEChERS. A mass analysis was carried out using simul-taneous scanning in both positive and negative ion mode and multiple reaction monitoring mode. All analytes showed good linearity, with correlation coefficients (R2) greater than 0.9923; their limits of quantification were 0.02-1.95 ng/mL. The average recoveries at low, medium, and high spiked levels were in the range of 70.1 %- 117.3 %, with intra-day precision ranging from 3.4 % to 16.9 % and inter-day precision ranging from 4.0 % to 19.3 %. The established analytical method was used to analyze the pesticide residue in swine urine and bovine urine collected from farms in Yining, Xinjiang, China. A total of 8 pesticides were detected, and the residue ranged from less than the limit of quantitation to 22.4 ng/mL. The top three pesticides with the highest detection frequency were clothianidin, thiamethoxam, and dinotefuran. The exposure assessment based on the monitored pesticide residue concentration levels showed that the detected pesticides could pose little risk to cattle and pigs.