Analysis of dexamethasone and prednisolone residues in bovine milk using matrix solid phase dispersion-liquid chromatography with ultraviolet detection

Dexamethasone and prednisolone are synthetic glucocorticoids, commonly used in veterinary practice for the treatment of illnesses such as respiratory and gastrointestinal diseases. They are also used illicitly as growth promoters, which practice is banned in the European Union and the therapeutic use is restricted by establishing maximum residue limits (MRLs) 0.3-2 mu g kg(-1) for dexamethasone and 4-10 mu g kg(-1) for prednisolone depending on the tissue type. Matrix solid phase dispersion (MSPD)-liquid chromatography with ultraviolet detection method was developed for the residue analyses of dexamethasone and prednisolone, validated according to European Directive requirements and tested on bovine milk derived from treated animals. MSPD offers extraction, clean-up and concentration in one step, making sample preparation easier and faster. Validation results and results of milk samples derived from treated animals proved, that the presented method can be applied to the determination of dexamethasone and prednisolone residues in cow's milk samples with a detection limit of 0.075 mu g kg(-1) for dexamethasone and 0.50 mu g kg(-1) for prednisolone. (C) 2008 Elsevier B.V. All rights reserved.