title: Modification and re-validation of the ethyl acetate-based multi-residue method for pesticides in produce.
abstract: The ethyl acetate-based multi-residue method for determination of pesticide residues in produce has been modified for gas chromatographic (GC) analysis by implementation of dispersive solid-phase extraction (using primary-secondary amine and graphitized carbon black) and large-volume (20 muL) injection. The same extract, before clean-up and after a change of solvent, was also analyzed by liquid chromatography with tandem mass spectrometry (LC-MS-MS). All aspects related to sample preparation were re-assessed with regard to ease and speed of the analysis. The principle of the extraction procedure (solvent, salt) was not changed, to avoid the possibility invalidating data acquired over past decades. The modifications were made with techniques currently commonly applied in routine laboratories, GC-MS and LC-MS-MS, in mind. The modified method enables processing (from homogenization until final extracts for both GC and LC) of 30 samples per eight hours per person. Limits of quantification (LOQs) of 0.01 mg kg(-1) were achieved with both GC-MS (full-scan acquisition, 10 mg matrix equivalent injected) and LC-MS-MS (2 mg injected) for most of the pesticides. Validation data for 341 pesticides and degradation products are presented. A compilation of analytical quality-control data for pesticides routinely analyzed by GC-MS (135 compounds) and LC-MS-MS (136 compounds) in over 100 different matrices, obtained over a period of 15 months, are also presented and discussed. At the 0.05 mg kg(-1) level acceptable recoveries were obtained for 93% (GC-MS) and 92% (LC-MS-MS) of pesticide-matrix combinations.
authors.affiliation: Rikilt Institute of Food Safety, Pesticides and Contaminants, P.O. Box 230, 6700 AE, Wageningen, The Netherlands. hans.mol@wur.nl
authors.forename: Hans G J
authors.initials: HG
authors.lastname: Mol
authors.forename: Astrid
authors.initials: A
authors.lastname: Rooseboom
authors.forename: Ruud
authors.initials: R
authors.lastname: van Dam
authors.forename: Marleen
authors.initials: M
authors.lastname: Roding
authors.forename: Karin
authors.initials: K
authors.lastname: Arondeus
authors.forename: Suryati
authors.initials: S
authors.lastname: Sunarto
mesh_terms: D000085:Acetates / Q000737:chemistry*; D000588:Amines / Q000737:chemistry; D002244:Carbon / Q000737:chemistry; D002849:Chromatography, Gas / Q000379:methods; D002853:Chromatography, Liquid; D005506:Food Contamination / Q000032:analysis*; D010573:Pesticide Residues / Q000032:analysis* / Q000737:chemistry; D010945:Plants, Edible / Q000737:chemistry*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D052616:Solid Phase Extraction / Q000379:methods*; D053719:Tandem Mass Spectrometry / Q000379:methods
chemical_list: D000085:Acetates; D000588:Amines; D010573:Pesticide Residues; D002244:Carbon; C007650:ethyl acetate