[Determination of 92 pesticide residues in tea by gas chromatography with solid-phase extraction]

A multiresidue analytical method was developed for the determination of ninety-two pesticides in tea using solid-phase extraction (SPE) and gas chromatographic determination. Tea samples were extracted with acetonitrile, organophosphorus pesticides were clean-up by an Envi-Carb SPE cartridge, eluted with 10 mL acetonitrile-toluene (3:1, v/v) and determined by gas chromatography-flame photometric detection (GC-FPD); organochlorine pesticides and pyrethroids pesticides were cleaned-up by Envi-Carb + NH2 SPE cartridges, eluted with 5 mL acetonitrile-toluene (3:1, v/v) and determined by gas chromatography-electron capture detection (GC-ECD). The recoveries of those pesticides were ranged from 80.3% to 117.1% by fortification test with the relative standard deviations being from 1.5% to 9.8%. The limits of detection were 0.0025 - 0.10 mg/kg. The proposed method is characterized by simplicity, higher sensitivity and accuracy.