Multi-residue Screening Method for the Determination of Non-steroidal Anti-inflammatory Drug Residues in Cow’s Milk with Hplc-uv and Its Application to Meloxicam Residue Depletion Study

A simple and short HPLC-UV screening method for the determination of residues for seven NSAIDs (carprofen, diclofenac, flunixin, meloxicam, phenylbutazone, tolfenamic acid, vedaprofen) and their three metabolites (4-methylaminoantipyrine, 5-hydroxyflunixin, oxyphenbutazone) in cow’s milk has been developed. The sample preparation was based on liquid-liquid extraction with acetonitrile in the presence of sodium chloride. The separation of analytes was performed on a C18 column with a gradient of acetonitrile and the ammonium acetate buffer pH 5.0. UV-detector wavelength was programmed in order to improve sensitivity. The method was validated according to the CD/2002/657 criteria. For most analytes, relatively high recoveries were observed (76%-98%). Within-laboratory reproducibility levels were in the range of 3.6%-17.8% (CV, %). For phenylbutazone, oxyphenbutazone, and 4-methylaminoantipyrine recoveries were considerably lower (44%-68%) and reproducibility was up to 41.9%, which was probably caused by the instability of analytes. The robustness of the method for different fat content was successfully investigated. The method was verified by its use in the determination of meloxicam residues in milk samples obtained from meloxicam-treated cows. The obtained results confirm the usefulness of the developed method for the analysis of NSAIDs residues in milk.