DEVELOPMENT AND VALIDATION OF AN HPLC CONFIRMATORY METHOD FOR THE DETERMINATION OF EIGHT CEPHALOSPORIN RESIDUES IN MILK, ACCORDING TO 2002/657/EC

摘要

Eight cephalosporins (cefadroxil, cefaclor, cephalexin, cefotaxime, cefazolin, cefuroxime, cefoperazone and ceftiofur) were isolated from milk after Matrix Solid Phase Dispersion, using Nexus sorbent. Sonication provided an efficient contact between the solid and the extractant, thus resulting in higher recovery rates of the target analytes. Multi-residue analysis was subsequently performed by HPLC-DAD. By using a monolithic analytical column, the separation of the compounds was achieved in 16 min. Validation of developed method was performed according to the European Union decision 2002/657/EC, determining linearity, selectivity, stability, decision limit, detection capability, accuracy, and precision. Recovery rates of examined antimicrobials from milk were in the range 93.4-108.6%. RSD values were lower than 15.3%. All observed LOQ values were lower than respective MRL values. In milk samples of different brands purchased from local market, no cephalosporins residues were detected.