Qualitative Screening and Quantitative Analysis of 110 Pesticides in Blood by Ultra-High Performance Liquid Chromatography- Quadrupole-Time of Flight Mass Spectrometry

A method of ultra-high performance liquid chromatography-quadrupole-time of flight mass spectrometry (UPLC-Q-TOF/MS) for simultaneous analysis of 110 pesticides in blood was established. 200 μL blood sample and 1 000 μL methanol were mixed in a 2 mL centrifuge tube, and the mixture was vortexed for 2 min to have the target extracted. After centrifuging for 10 min, the supernatant was analyzed under the optimized instrumental conditions. A Kinetex Biphenyl chromatographic column was used as the stationary phase, and a mixed solution containing of 5 mmol·L^-1 ammonium formate solution (A) and methanol solution containing 5 mmol·L^-1 ammonium formate (B) was used as the mobile phase for gradient elution. Under the mode of ESI⁺ and IDA, primary and secondary mass spectrometry information were collected in sequence. Qualitative screening was performed using Master View software through a combined score obtained from 4 factors including mass error, retention time error, isotope ratio difference and library similarity; Multi Quant software was used for quantitative analysis by the peak area of the precursor ion in XIC chromatogram. The results showed that the combined scores of 110 target pesticides were ranged from 81.8 to 97.0 points, all above the minimum score of qualitative screening (80 point). The mass concentrations of 110 target pesticides were linearly related to the corresponding chromatographic peak areas in the range of 5-200 μg·L^-1, and the correlation coefficients were all above 0.99. The limits of detection (3S/N) found were same of 2 μg·L^-1. The spiked recovery test was made by using the blank blood as matrix at 3 concentration levels, giving the recoveries of the target pesticides in the range of 80.3%-120%, and RSDs (n=6) of the determined values were ranged from 1.9% to 20%. The matrix effects were evaluated by the ratio of the peak area of the same compound with the same mass concentration between the standard solution and the blank matrix matching solution, and matrix effects of 110 pesticides were found in the range of 80.65%-119.86%. Blood samples from two pesticide poisoning cases were analyzed by the present method, and dichlorvos, chlorpyrifos, cypermethrin (for case 1) and atrazine, cyfluthrin, carbofuran (for case 2) were detected, with combined scores all above 80 point, and their mass concentrations were 183.98, 156.79, 104.67 μg·L^-1 and 144.57, 165.32, 138.91 μg·L^-1, respectively.