Evaluation and interlaboratory validation of a GC-MS method for analysis of pesticide residues in teas

Abstract

A method was described for simultaneous determination of nine organic heterocyclic pesticide residues by gas chromatography-mass spectrometry-selected ion monitoring. Atrazine, vinclozolin, procymidone, triflumizole, imazalil, buprofezin, propiconazole, fenarimol, and pyridaben were clearly separated from each other, extracted with acetone—hexane mixture, purified with graphitized carbon black cartridge and neutral Al₂O₃ cartridge, eluted with acetone—hexane mixture, simultaneously determined by GC-MS, and then quantified with an external standard method. Recoveries of pesticides ranged from 73 % to 116 % at the spiked level of 0.01–30 mg kg⁻¹, while the relative standard deviation was between 3 % and 27 %. In addition, the limits of determination (0.01 mg kg⁻¹ to 5.0 mg kg⁻¹) and linearity (0.02–40 μg mL⁻¹) revealed that simultaneous determination of multi-residues in Chinese teas (like Oolong tea, green tea, red tea, etc.) was possible. Furthermore, an interlaboratory study among 5 labs was conducted to further validate the method, and the results were satisfactory.