Simultaneous determination of 131 pesticides in tea by on-line GPC-GC-MS/MS using graphitized multi-walled carbon nanotubes as dispersive solid phase extraction sorbent.

A rapid and sensitive method was developed to determine 131 pesticides in tea by on-line gel permeation chromatography-gas chromatography tandem mass spectrometer (on-line GPC-GC-MS/MS) using graphitized multi-walled carbon nanotubes (MWCNTs) as dispersive solid phase extraction (DSPE) sorbent in sample pretreatment. Sample clean-up performance of various functionalized MWCNTs and their influences to recoveries were investigated. In the method validation, good linearity correlation coefficients (R2) were obtained, which were higher than 0.99 for all pesticides. The percent recoveries were 78.2%-113.9% at the spiked concentration levels of 20, 50 and 200 µg/kg with relative standard deviations (RSDs, n = 6) lower than 15.8%. Limits of detections (LODs) were in the range of 0.5-5.0 µg/kg. This method is simple and fast with relatively high sensitivity and can achieve the requirements of pesticides analysis.