Determination of 21 Pesticide Residues in <i>Cornus officinalis</i> Sieb. et Zucc. by UPLC-MS/MS

Purpose: A method based on dispersive solid-phase extraction (dSPE) combined with ultra-high performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) was applied for the simultaneous determination of 21 pesticide residues in Cornus officinalis Sieb. et Zucc., a food-medicinal homologous substance. Additionally, commercial samples were tested to evaluate their quality. Methods: Samples were extracted with acetonitrile-water (10: 5, v/v). The extract was purified by dSPE using 200 mg anhydrous magnesium sulfate + 50 mg primary secondary amine (PSA) + 50 mg C18 as matrix dispersants. Gradient elution was performed using a mobile phase consisting of 0.01% formic acid, 2 mmol/L ammonium formate aqueous solution and 0.01% formic acid in methanol. UPLC-MS/MS with electrospray ionization (ESI) in positive ion mode and multiple reaction monitoring (MRM) was employed for detection. Matrix-matched standard curves were prepared, and quantification was carried out by the external standard method. Results: All 21 target pesticides showed good linearity in the concentration range of 2 ng/mL-200 ng/mL (r ≥ 0.994). The limits of quantification (LOQ) for all pesticides were less than 7.6 μg/kg. At three spiked levels (5 μg/kg, 20 μg/kg, and 50 μg/kg), the recoveries of the 21 pesticides ranged from 72.24% to 115.0%, with relative standard deviations (RSDs) of 0.40% to 9.7%. Conclusions: The developed method meets the requirements for pesticide residue levels of insecticides, making it suitable for rapid confirmation and quantitative analysis of 21 pesticide residues in Cornus officinalis Sieb. et Zucc.