Determination of Organophosphorus Pesticide Residues in Onion and Welsh Onion by Gas Chromatography with Pulsed Flame Photometric Detector

摘要

A rapid gas chromatograhic method for determining organophosphorus pesticide residues in allium such as onion and welsh onion containing high levels of sulfur-matrices was studied.A sampl was extracted with acetonitrile and the acetonitrile layer separated by salting-out.The extract was cleaned up with gel permeation chromatography,and then with a tandem silica-gel/PSA mini-column.The test solution was subjected to gas chromatography with a pulsed flame photometric detector.organophosphorus pesticide residues in such sulfurrich matrices were determined without any serious interfering peaks on the chromatograms by diluting the extracts 8-fold (0.25 g/ml of sample).No additional pretreatment to deactivate enzymes which caused interference was necessary.The rate of recovery of 36 organophosphorus pesticides from fortified onion and welsh onion ranged from 61 to 105% with the RSD usually <10% for five experiments.The detection limits of these pesticides were good (0.002-0.01 mg/kg)for monitoring organophosphorus pesticide residues in agricultural products including allium,except for degradable trichlorfon.The method was applied to onion and welsh onion to demonstrate its use in routine analysis.