A novel method based on MSPD for simultaneous determination of 16 pesticide residues in tea by LC-MS/MS

A novel method based on matrix solid phase dispersion (MSPD) coupled with liquid chromatography-tandem mass spectrometry was established for the determination and the quantification of 16 pesticides (5 carbamates, 4 organophosphorus, and 7 pyrethroids) in various tea. Matrix dispersive sorbent and further cleanup sorbent were applied to improve the efficiency of extraction and purification. PVPP, PSA and GCB were introduced as further cleanup sorbents packed at the bottom of the MSPD to remove co-eluting matrix components. Different experiment conditions, such as type of eluting solvent, its volume, matrix dispersive sorbent, sample to matrix dispersive sorbent mass ratio, and the dosage of cleanup sorbents were thoroughly studied and optimized. It was found that polyvinylpolypyrrolidone (PVPP), an inexpensive and excellent absorbent, could effectively remove polyphenols in tea, which was seldom reported before. The method showed satisfactory linearity over the range assayed 0.9986-0.9999 (1-500ngg(-1) for 5 carbamates and 4 organophosphorus, 2-800ngg(-1) for 7 pyrethroids), the limits of detections (LODs) ranged from 0.01 to 1.38ngg(-1), and the limits of quantifications (LOQs) were ranging from 0.03 to 4.74ngg(-1). The recoveries using this method at three spiked concentration levels (10, 100, and 500ngg(-1)) range from 87.7 to 99.6%. The relative standard deviation (RSD) was from 0.2 to 9.6% in all case. The proposed analytical method has been successfully applied for the analysis of 16 pesticides in commercial tea.