Determination of nine pyrethroid pesticide residues in tea by gas chromatography-tandem mass spectrometry combined with accelerated solvent extraction and solid phase extraction

Abstract

A method has been developed for the simultaneous detection of nine pyrethroid pesticide residues in tea by gas chromatography-tandem mass spectrometry (GC-MS/MS) combined with accelerated solvent extraction (ASE) and solid-phase extraction (SPE). The pesticide residues in tea were extracted using acetone/n-hexane (1:1, v/v) for 5 min at 100℃ before preheating the extraction pool for 3 min, under extractive pressure of 10 MPa for one cycle. After extraction, the extraction pool was washed with acetone/n-hexane (1:1, v/v) having volume of 40% of the pool volume, followed by purging for 100 s with nitrogen. The extract was purified by a Cleanert TPT solid-phase extraction column. After purification, the target compounds were detected by GC-MS/MS and quantified by the external standard method. Under the optimized conditions, good linearities were obtained for the nine pyrethroid pesticides in the range of 2-1000 μg/L, with correlation coefficients exceeding 0.99. The limits of detection (LODs) were 0.2-4.5 μg/kg and the limits of quantitation (LOQs) were 0.8-15.0 μg/kg. At four spiked levels (0.02, 0.1, 0.4 mg/kg, and the LOQ level) in green tea and black tea, the recoveries of all the pesticides were between 69.87% and 110.0%, with relative standard deviations (RSDs) varying from 0.7% to 11.2%. This method effectively reduces the matrix interference and shows high sensitivity, good reproducibility, and stable recovery, and can thus be used for the detection of pyrethroid pesticide residues in tea.