Abstract: This study intended to develop a method for the determination of 23 organophosphorus pesticide residues in tea by gas chromatography (GC). The target pesticides in tea were extracted by a modified QuEChERS method with acetone as the solvent, followed by cleanup with N-propyl ethylenediamine (PSA) adsorbent and multi-walled carbon nanotubes (MWCNTs). The quantification was performed by the matrix external standard method. Good linearity was observed for all calibration curves with correlation coefficients (r) > 0.986 5 over the range of 0.02–1.00 μg/mL. The limits of detections (LODs) were 0.01–0.02 mg/kg, and the limits of quantitation (LOQs) were 0.03–0.06 mg/kg. The recoveries at three spiked levels (0.05, 0.50 and 1.00 mg/kg) varied from 81.8% to 107.2%, with relative standard deviations (RSDs) of 1.2%–7.2%. Compared with the traditional QuEChERS method, this method was easy, fast and solvent saving with good recovery and accuracy. Thus, it was suitable for the determination of 23 organophosphorus pesticide residues in tea.

Key words: tea, QuEChERS, gas chromatography (GC), organophosphorus pesticide residues, multi-walled carbon nanotubes (MWCNTs)