Optimization of gas chromatography-single quadrupole mass spectrometry conditions for multiresidue analysis of pesticides in grapes in compliance to EU-MRLs

A single quadrupole GC-MS method was optimized for multiresidue determination of 47 pesticides in grapes with limit of quantifications of each compound in compliance with the EU-MRL requirements. Sample preparation involved extraction of 10 g sample with 10 ml ethyl acetate (+10 g sodium sulphate) by homogenization at 15,000 rpm followed by centrifugation at 3000 rpm. The supernatant was cleaned by dispersive solid phase extraction with primary secondary amine and acidified with 0.1% formic acid. Residues were estimated in selected ion monitoring mode with programmable temperature vaporizer-large volume injection (8 mu l). All the GC and MS parameters were thoroughly optimized to achieve satisfactory linearity (R-2 > 0.99) within 0.01-0.25 mg kg(-1) with minimum matrix interferences. Recoveries at 0.01 and 0.02 mg kg(-1) were within 67-120% with associated precision RSD below 19%. The method was successfully applied for analysis of the real world samples for incurred residues. (C) 2012 Elsevier Ltd. All rights reserved.