Determination of cephalosporins in raw bovine milk by high-performance liquid chromatography

A high-performance liquid chromatographic (HPLC) method based on solid-phas e extraction was developed for the determination of cefazolin, cefoperazone , cefquinome and ceftiofur in raw bovine milk. The milk fat was removed by centrifugation and the cephalosporins were extracted in acetonitrile. The e xtract was cleaned up by solid-phase extraction on an octadecyl sorbent. Th e compounds were separated by ion-paired gradient HPLC on a phenyl column w ith ultraviolet detection at 270 nm. The limits of detection estimated by a conservative model were 11 mu g/kg for cefazolin and cefoperazone and 7 mu g/kg for cequinome and ceftiofur. The mean recoveries were 86-88% for cefa zolin, 91-93% for cefoperazone, 69-72% for cefquinome and 84-88% for ceftio fur in the concentration range 20-200 mu g/kg, (C) 2000 Elsevier Science B. V. All rights reserved.