Novel use of PVPP in a modified QuEChERS extraction method for UPLC-MS/MS analysis of neonicotinoid insecticides in tea matrices

A rapid UPLC-ESI (+)-MS/MS method was developed and validated for simultaneous determination of eight neonicotinoid insecticides (dinotefuran, nitenpyram, thiamethoxam, clothianidin, imidacloprid, acetamiprid, thiacloprid and imidaclothiz) in tea samples based on a refined QuEChERS extraction method. In order to eliminate the matrix effect and obtain satisfactory recoveries, an inexpensive and excellent absorbent material, polyvinylpolypyrrolidone (PVPP), was used to eliminate polyphenols from tea matrices. Further, combinations of PVPP and the commonly used sorbents PSA and GCB were investigated in this study. The optimized 'quick, easy, cheap, effective, rugged and safe' protocol is briefly described as follows. Tea samples were soaked in water and extracted with acetonitrile. Sample extracts were treated with 400 mg PVPP to remove polyphenols from tea matrices, and then cleaned up with a combination of PSA (25 mg), GCB (100 mg) and C18 (50 mg). Finally, the dried extract was dissolved in acetonitrile/water (15 : 85, v/v) and analyzed by UPLC-MS/MS. The recovery ratios from tea for eight neonicotinoid insecticides ranged from 60-109% at 0.01-0.5 mg kg(-1) spiked levels. Relative standard deviations were <15.4% for all of the recovery tests. The limit of quantification was below 0.01 mg kg(-1). The developed method was simple, effective, and sensitive. This method should prove to be highly useful for monitoring neonicotinoid insecticides in commercial tea products.