Adaptation of capillary electrophoresis to the determination of selected cephalosporins for injection.

The migration behaviour of cephazolin, cefuroxime sodium, ceftriaxone sodium, cefoperazone sodium and ceftazidime in a mixture was studied. Phosphate-borate buffer pH 5-8 alone and with addition of sodium dodecylsulfate (SDS) was used. In capillary zone electrophoresis of all research compounds separation was not achieved. It was observed that supplementation buffer pH 6.5 with SDS (10 g/l) improved resolution of cephalosporins, but addition of pentanesulfonic acid (17.4 g/l) to the running buffer at pH 6.5 results in separation of each cephalosporin. In this condition good repeatability of migration times as well as repeatability of peak area were confirmed.