Determination of multi-pesticides in black tea by subcritical water extraction and gas chromatography-tandem mass spectrometry

Abstract

A gas chromatography-tandem mass spectrometry (GC-MS/MS) method with subcritical water extraction was developed for the determination of 21 organochlorine and pyrethroid pesticides in black tea. Under the extraction pressure of 5 MPa, the target compounds were extracted with subcritical water at the temperature of 150 degrees C for 15 min, transferred into acetone-n-hexane (1:1, v/v), and cleaned-up by an ENVI-Carb solid phase extraction (SPE) column. The GC separation was performed on a DB-5 capillary column. The pesticides were determined by MS/MS in multiple reaction monitoring (MRM) mode and quantified by matrix-matched internal standard method. The calibration curves showed good linearities in the range of 5.0-320.0 microg/L with the correlation coefficients greater than 0.99. The limit of quantification (S/N > 10) was 50 ng/g, and the limit of detection (S/N > 3) was 10 ng/g. The recoveries of pesticides spiked in the tea at three levels of 50, 100 and 200 ng/g were ranged from 70. 18% to 119.98% with the relative standard deviations (RSDs) of 5.01%-11.76%. The sensitivity, accuracy and precision of the method meet the technical standard of the pesticide determination. The method can be applied to the determination of organochlorine and pyrethroid pesticides in black tea.