Quantification of 397 pesticide residues in different types of commercial teas: Validation of high accuracy methods and quality assessment

•Sensitivity and accuracy methods were validated for 397pesticides in different teas.•191 pesticides were quantified by using solvent calibration curves inUPLC-MS/MS.•Calibration curves in 4 teas mixed-blank could overcome matrix effects in GC-MS/MS.•106 teas from several origins were analyzed and 25% exceeding EU MRLsregulations.•Neonicotinoids, pyrethroids and triazole fungicides were mostlydetected in teas. Analytical methods with high sensitivity and accuracy were successfully validated for the quantification of 397 pesticides in different types of tea. For the UPLC-MS/MS method, 191 pesticides of 200 ones in total had “soft” matrix effects and could be quantified by calibration curves in the solvent. For the GC-MS/MS method, matrix-matched calibration curves were established on a mixed blank including white, green, oolong and black organic teas. The method limit of quantifications ranged from 1.0 µg kg−1 to 10 µg kg−1 (UPLC-MS/MS) and 1.0 µg kg−1 to 50 µg kg−1 (GC-MS/MS), with 70–120% of recovery. These methods was subsequently applied to 106 tea samples from several origins, in which 26 samples contained at least one pesticide violation, with a total of 43 pesticide residue violations. The most frequently detected pesticides were neonicotinoids, synthetic pyrethroids, and triazole fungicides. Taiwan had the most pesticide-contaminated samples followed by China, Vietnam, and India.