Validation and uncertainty analysis of a multiresidue method for 42 pesticides in made tea, tea infusion and spent leaves using ethyl acetate extraction and liquid chromatography-tandem mass spectrometry

A rapid. specific and sensitive multiresidue method to determine 42 pesticides in made tea. tea infusion and spent leaves has been developed and validated for the routine analysis by liquid chromatography-tandem mass spectrometry (LC-MS/MS) The method was reproducible (Horwitz ratio (HorRat) <0 5 at 50 ng/g) and validated by the analysis of sample spiked at 50 and 100 ng/g in made tea, tea infusion and spent leaves The samples were extracted with ethyl acetate+ cyclohexane (9 1, v/v), and the extracts were cleaned up by dispersive solid phase extraction with primary secondary amine sorbent + graphitized carbon black + Florisil The recoveries of all the pest icicles were between 70% and 120% with a relative standard deviation of less than 15% and correlation coefficient for each pesticide was R-2 >= 099 The matrix effect on signal of respective compounds was measured by comparing matrix-matched calibration standards with those in solvent-only The limits of quantitation (LOQ) met the requirements of the maximum residue limits (MRLs) for pesticides in tea as recommended by the European Union. (C) 2010 Elsevier B V All rights reserved