Abstract:

A method using gas chromatography (GC) with flame photometric detection was developed for the simultaneous determination of 9 organophosphorus pesticide multiple residues in tea matrices. A total of 30 Pu-erh tea samples from 5 producing areas in Yunnan province (half raw tea and half ripe tea, with 3 replicates for each area) were determined by the developed method in order to provide experimental data for safety assessment. Samples were extracted with ethyl acetate under the assistance of ultrasonic, followed by clean-up on an activated carbon cartridge. Quantification was achieved using external standard method. Mean recoveries for 9 analytes at 3 spike levels ranged from 71.1% to 113.8%, with a RSD between 0.9% and 13.3%. The developed method exhibited limits of detection ranging from 1.0 to 2.5μg/kg. Dichlorovos, acephate, dimethoate, fenitrothion, malathion, quintozene and triazophos were all detected in selected Pu-erh tea samples. Among them, the detection rates of fenitrothion and dimethoate were higher, but the contents were both lower than the EU limit standard. In terms of organophosphorus pesticide multiple residues in Pu-erh tea, it is safe for drinking.

Key words: Pu-erh tea, organophosphorus pesticide, residue determination