Determination of pyrethroid pesticide residues by gas chromatography-negative chemical ionization mass spectrometry and its application

A solid phase extraction (SPE)-gas chromatography (GC)-negative chemical ionization mass spectrometry (NCI/MS) method was proposed for analyzing 11 kinds of pyrethroid pesticides in tea. Pesticide residues were extracted from tea samples with ethyl acetate. And extract was cleaned-up by active carbon SPE column connected to alumina neutral SPE column. Analytical screening was determined by the technique of gas chromatography-negative chemical ionization mass spectrometry-selected ion monitoring. The recoveries of all pyrethroid pesticides were in the range of 70%-110% at three spiked level, 0.016, 0.032 and 0.064 mu g/kg, and the relative standard deviations were below 7.4%. The limit of detections of all pesticides were from 0.02 to 10 mu g/kg. The method is reliable and stable.