Simultaneous Determination of 26 Pesticide Residues in Traditional Chinese Medicinal Leeches by Modified QuEChERS Coupled with HPLC–MS/MS

[Image: see text] A Quick, Easy, Cheap, Effective, Rugged, and Safe (QuEChERS) pretreatment technique combined with HPLC–MS/MS was established to detect 26 pesticides in traditional Chinese medicinal leeches. The sample was extracted by acetonitrile solution with sodium acetate-0.1% (v/v) acetic acid as a buffer system, then cleaned up by a mixture of 750 mg of MgSO(4), 150 mg of C(18), and 150 mg of PSA, separated by an ACQUITY BEH C(18) column, and determined in the dynamic multiple reaction mode. Under the optimized conditions, the peak areas of the 26 pesticides in leeches showed good linearity (r > 0.99) between their mass concentrations from 1 to 100 μg/L. At the spike levels of 10, 20, and 100 μg/kg, the recoveries of 26 pesticides in leeches were 72.9–101.6% with an RSD of 1.1–12.8%, an LOQ of 10 μg/kg, and an LOD of 0.1–5.4 μg/kg. This method is easy, rapid, sensitive, and practical and meets the requirements of pesticide residue detection standards.