A multi-residue method for fast determination of pesticides in tea by ultra performance liquid chromatography–electrospray tandem mass spectrometry combined with modified QuEChERS sample preparation procedure
A multi-residue method was developed for rapid determination of pesticide residues in tea by ultra performance liquid chromatography–electrospray tandem mass spectrometry (UPLC/MS/MS). The QuEChERS method was used for sample preparation. In order to minimise the matrix effects from tea, a solid phase extraction (SPE) cartridge layered with graphite carbon/aminopropylsilanized silica gel was applied as complementary to QuEChERS method. For accurate quantification, representative matrix-matched calibration curves were applied to compensate matrix effects. Limits of quantification varied with different pesticides but all can be measured at 0.01 mg kg−1 level in a 5 g tea sample except dichlorvos (0.02 mg kg−1). Recoveries ranged from 70% to 120% and relative standard deviation (RSD) met the European United Quality Control guideline. Efficiency and reliability of this method were investigated by the analysis of both fermented and unfermented Chinese tea samples.