Abstract:

A rapid determination method of 21 organophosphorus pesticides in tea was developed by QuEChERS method using modified multi-walled carbon nanotubes (MWCNTs-OH), primary-secondary amine (PSA) and MgSO₄ coupled with gas chromatography-mass spectrometry. The pesticide residues in tea were extracted with a hexane-acetone (2 : 1, v/v) mixture, and cleaned up by dispersive solid-phase extraction using MWCNTs-OH and primary-secondary amine (PSA) as the sorbents. After centrifugation and filtration, the target compounds were analyzed by gas chromatography-mass spectrometry and quantified by the external standard method. Under the optimized conditions, good linearities were obtained in the range of 0.01-0.50 mg/kg. The average recoveries were in the range of 81.5%-109.4% at three spiked levels, with relative standard deviations (RSDs, n=5) of 2.3%-10.6%. The limits of quantification were 0.001-0.040 mg/kg. This method is simple, fast, sensitive, cheap, and can meet the requirements of the rapid detection of organophosphorus pesticides in tea.

Key words: dispersive solid-phase extraction (DSPE), gas chromatography-mass spectrometry (GC-MS), hydroxylated multi-walled carbon nanotubes, organophosphorus pesticides, tea