Determination of Organochlorines and Pyrethroids Residues in Tea from Jiangxi Province with Microwave-Assisted Extraction-Gas Chromatography

A new method for multiresidue analysis of 18 organochlorines and 9 pyrethroids in tea from Jiangxi province was established.The pesticide residues were extracted from tea samples with hexane-dichloromethane(1:2,V/V) by using microwave-assisted methed,and the microwave-assisted extraction conditions,such as the extraction solvent type,volume,microwave heating time and microwave temperature were optimized with orthogonal test design.The extracts were purified with alumina neutral-florisil column,and then determined with gas chromatography equipped with electron-capture detector(GC-ECD),using DB-1701 capillary column.The recoveries obtained from Chinese tea samples(n=5) added with pesticide standards at the three levels of 0.4,0.2 and 0.1ml(0.5 μg/ml organochlorines plus 1.0 μg/ml pyrethroids) are in the ranges of 80.9% to 118.5%,88.4% to 120.7% and 80.9% to 116.3% with the RSDs in the ranges of 2.09% to 6.70%,1.89% to 6.49% and 1.98% to 11.87%,respectively.The detection limits of the organochlorine pesticides are in the range of 0.0004 to 0.0015 mg/kg,and those of the pyrethroids are in the range of 0.0067 to 0.0365 mg/kg.