Multi-residue determination of 41 insecticides in garlic by gas chromatography and ion trap mass spectrometry using the selective ion storage technique

A method is described for determining 41 insecticide residues in garlic (Al lium sativum L.), including organophosphorus, organochlorine, carbamate, an d synthetic pyrethroid insecticides. These insecticides were extracted from samples with acetone and dichloromethane, and coextractives removed using a charcoal/Celite/alumina column. Analysis was performed by gas chromatogra phy with ion trap mass spectrometry in selective ion storage (SIS) mode. Re tention times and specific ions (m/z values) were used to confirm insectici des. Recoveries for most insecticides (blank samples spiked at 0.05, 0.2 an d 1 mug mL(-1) levels) ranged from 70% to 110%, the coefficient of variatio n (CV) of the method was <20% for every case, and the limit of detection (L OD), defined in terms of 3 times baseline noise, varied between 0.01 and 0. 16 mg kg(-1), depending on the compound. Copyright (C) 2001 John Wiley & So ns, Ltd.