Abstract:

Gas chromatography is widely used in county-level agricultural product quality and safety testing institutions, and was used to detect 43 pesticide residues in pak choi samples numbered LAB-156 in the proficiency testing of pesticide residue detection for planting products in Guangdong Province in 2023. The results showed that five pesticides such as triazophos, acephate, methidathion, triadimefon and fenvalerate were added to the positive test samples of pak choi, and the other 38 kinds of pesticides were not detected. The detection values of quantitative detection were 0.086 8, 0.084 9, 0.118 0, 0.102 0 and 0.099 2 mg·kg^-1, respectively. The recovery rates of pesticide residues in the quality control standard samples of the same batch were between 79.0%-99.2%. Combined with the spiked values announced by the organizer at a later stage, the recovery rates of triazophos, acephate, methidathion, triadimefon and fenvalerate in the test samples were 108.5%, 84.9%, 98.3%, 102.0% and 99.2%, respectively, which were all within the qualified range of 70.0%-120.0%, and there was no missed or multiple detection. It can be judged that the test results of 43 kinds of pesticide residues in the numbered LAB-156 samples were qualified. The results of this study can be used as a reference for the determination of pesticide residues in planting products by county-level agricultural product quality and safety testing institutions.

Key words: gas chromatogaraphy, proficiency testing, planting, pesticide residues