METHODOLOGY FOR ANALYSING PESTICIDE MULTI- RESIDUE IN WUYI ROCK TEA USING MODIFIED QUECHERS FOLLOWED BY GAS CHROMATOGRAPHY-TANDEM MASS SPECTROMETRY

Tea is one of the most commonly consumed drinks worldwide, the production of which often uses a variety of multi-class pesticides. Development of a reliable method to determine the presence and quantity of any pesticide residue is therefore highly important. In the present study, we developed a validated method for the analysis of 33 pesticides in Wuyi Rock tea using the QuEChERS sample preparation method and capillary gas chromatography-tandem mass spectrometry (GC-MS/MS). After extracting the target components from the tea matrix using acetonitrile, a mixture of adsorbents [primary secondary amine (PSA; 400 mg), graphite carbon black (GCB; 400 mg), octadecylsilane (C18; 100 mg)] and salting-out solvents [anhydrous NaCl (1 g) and MgSO4 (4 g)] were used for clean-up, and an analyte protectant solution [sorbitol (10 mg/mL) and L-gulonic acid-gamma-lactone (20 mg/mL)] was added. For accurate quantification, a matrix-matched calibration method was applied. For all pesticides at concentration levels of 20-500 ng/ml, good linear calibrations with coefficients of (R-2) >= 0.994 were acquired. The recovery values of samples spiked with 20, 100, and 400 ng/kg doses of analytes ranged from 72.3 to 110.6%, and the relative standard deviations (RSD) ranged from 2.8 to 6.7%. The repeatability and recovery rates were in-line with criteria set by the GB 2763-2019 Guideline. Therefore, this validated method is suitable for the simultaneous determination of multi-class pesticide residues in Wuyi Rock tea.