Abstract: Objective To establish an ultra-high performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS) method for screening 135 pesticide residues in Farfarae Flos. Methods Acetonitrile was used as the extraction solvent, and high speed homogenate was used for extraction. The chromatographic column was CORTECS^TM UPLC (C₁₈, 1.6 μm,2.1 mm×150 mm). The mobile phase was composed of 0.1% formic acid (containing 5mmol·L^-1 ammonium formate) solution as the aqueous phase, and 95% acetonitrile solution (containing 5 mmol·L^-1 ammonium formate and 0.1% formic acid) as the organic phase under gradient elution. The flow rate was 0.3 mL·min^-1, column temperature was 40℃, and injection volume was 2 μL. The electrospray ion source was used in the multi-reaction monitoring mode. The contents were calculated with the standard curve method. The chronic hazard quotient (HQ_c) was calculated via chronic exposure assessment. Results The recoveries of the 135 pesticides ranged from 70.30% to 118.45%, and the relative standard deviation was less than 9.1%. The measured components showed a good linear relationship (r ≥ 0.99) in the range of 1~100 ng·mL^-1. Seven batches of chlorpyrifos, one batch of nitridazole and one batch of carbaryl were screened out from 27 batches of samples. The HQ_c of all the batches was far less than 1, and the risk of pesticide residues of Farfarae Flos was low. Conclusion This method is multi-functional, accurate and fast, which is suitable for the high throughput determination and risk assessment of 135 pesticide residues in Farfarae Flos, and is of referential value for the detection of pesticide residues in other Chinese medicinal materials.

Key words: Farfarae Flos, pesticide residues, chlorpyrifos, myclobutanil, carbaryl, risk assessment, ultra-high performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS)