GC-MS/MS Determination of Residual Amounts of 24 Pesticides in Tea

GC-MS/MS was applied to the determination of residual amounts of 24 pesticides in tea. The sample was extracted ultrasonically with acetonitrile and the extract was cleaned up on Cleanert TPT solid phase extraction column which was eluted with a mixture of acetonitrile-toluene (3+1). RTX-5MS chromatographic column was used for GC separation and the multiple reaction monitoring mode was adopted in MS determination. Internal standard method was used for quantification. Linearity ranges of the 24 pesticides were found in the same range of 0.005-1.0 mg·L-1 with detection limits (3S/N) in the range of 0.2-1.2 μg·kg-1. Tests for recovery were made by standard addition method at the concentration levels of 0.01,0.1,1.0 mg·kg-1,giving values of recovery and RSD′s (n=6) in the ranges of 67.5%-122% and 0.60%-9.9%,respectively.