RESUMO
A simple method permitting the simultaneous determination of trace residues of novobiocin and phenylbutazone in raw milk samples using liquid chromatography-tandem mass spectrometry was developed. Raw milk samples were mixed with acetonitrile to facilitate the concurrent precipitation of milk proteins and extraction of both veterinary drugs. Without additional clean-up or concentration of the resulting extract, the analytes could be quantified at concentrations as low as 0.0025 and 0.001 microg ml(-1) for phenylbutazone and novobiocin, respectively. The analysis of a series of fortified raw milk samples at analyte concentrations ranging from 0.005 to 0.1 microg ml(-1) and from 0.01 to 0.2 microg ml(-1) for phenylbutazone and novobiocin, respectively, yielded average recoveries ranging from 89.2% to 104.3% with standard deviations below 7%. The analytical method was applied to the analysis of raw milk samples collected from transport trucks upon delivery at dairy-processing plants throughout Alberta, Canada. Novobiocin was detected in 13 of 1072 samples tested at concentrations ranging from 0.001 to 0.007 microg ml(-1). Phenylbutazone was not detected in any of the samples tested.
Assuntos
Antibacterianos/análise , Anti-Inflamatórios não Esteroides/análise , Resíduos de Drogas/análise , Inspeção de Alimentos/métodos , Leite/química , Novobiocina/análise , Fenilbutazona/análise , Animais , Antibacterianos/química , Anti-Inflamatórios não Esteroides/química , Canadá , Cromatografia Líquida de Alta Pressão , Resíduos de Drogas/química , Resíduos de Drogas/normas , Contaminação de Alimentos/prevenção & controle , Inspeção de Alimentos/normas , Limite de Detecção , Novobiocina/química , Uso Off-Label/veterinária , Fenilbutazona/química , Espectrometria de Massas por Ionização por Electrospray , Espectrometria de Massas em Tandem , Estados Unidos , Drogas Veterinárias/análise , Drogas Veterinárias/químicaRESUMO
A simple method for the direct determination of residues of ionophore antibiotics and avermectin antiparasitics in surface water is reported. Using a large volume injector, a mixture of methanol and surface water is injected into an analytical liquid chromatography (LC) column and subsequently screened for residues of these veterinary pharmaceuticals using electrospray ionization tandem mass spectrometry. On-line sample enrichment and chromatographic separation are achieved using a single, short (20mm) octadecylsilane LC column. The method permits the detection of four ionophores and two avermectins in surface water samples at low ng L(-1) concentrations. Minimal matrix effects were observed for a variety of surface water samples which permitted the use of reagent-based standards for quantitation.