title: Particle beam liquid chromatography-mass spectrometry method with negative ion chemical ionization for the confirmation of oxacillin, cloxacillin and dicloxacillin residues in bovine muscle.
abstract: To ensure human food safety, the European Union has defined maximum residue limits (MRLs) for veterinary drug residues in food products. Analytical methods need to be developed to confirm the presence of drugs at the MRL level. A method using particle beam liquid chromatography-mass spectrometry was developed for the confirmation of oxacillin, cloxacillin and dicloxacillin in bovine muscle at the maximum residue limit of 300 micrograms kg-1. Beta-lactams were extracted from tissues with ethyl acetate under slightly acidic conditions and separated on a C18 bonded silica column with a methanol-aqueous formic acid (2%) solution-acetonitrile mobile phase. Negative ion chemical ionization with methane as the reagent gas was used to identify the compounds. The specificity required for a regulatory confirmation procedure was achieved by monitoring five fragment ions for each compound (selected ion monitoring mode): m/z 183, 198, 213, 214 and 241 for oxacillin; m/z 196, 248, 250, 275 and 277 for cloxacillin; m/z 165, 230, 232, 274 and 276 for dicloxacillin.
authors.affiliation: Ministère de l'Agriculture et de la Forêt, Centre National d'Etudes Vétérinaires et Alimentaires, Eougeres, France.
authors.forename: D
authors.initials: D
authors.lastname: Hurtaud
authors.forename: B
authors.initials: B
authors.lastname: Delepine
authors.forename: P
authors.initials: P
authors.lastname: Sanders
mesh_terms: D000818:Animals; D002417:Cattle; D002851:Chromatography, High Pressure Liquid / Q000379:methods; D003023:Cloxacillin / Q000032:analysis*; D004009:Dicloxacillin / Q000032:analysis*; D004350:Drug Residues / Q000032:analysis*; D005410:Flame Ionization / Q000379:methods; D006801:Humans; D013058:Mass Spectrometry / Q000379:methods; D008460:Meat / Q000032:analysis*; D018482:Muscle, Skeletal / Q000737:chemistry*; D010068:Oxacillin / Q000032:analysis*; D012449:Safety; D012680:Sensitivity and Specificity
chemical_list: D004009:Dicloxacillin; D003023:Cloxacillin; D010068:Oxacillin