Characterization of cephalosporin transfer between aqueous and colloidal phases by micellar electrokinetic chromatography

A new electrokinetic chromatographic method was applied to the determinatio n of the partition coefficient between water and micelle for a group of cep halosporins (cefmetazol, cephradin, cefaclor, ceftazidim, cefodizim, cephap irin, cephalothin and ceftriaxon) using sodium dodecyl sulphate as an anion ic surfactant in microemulsion and in micellar systems. In the new method, the running buffer contains both the micelles and the drug, and the injecte d solution contains the same concentration of micelles as the running buffe r but not the drug. The mobility of the drug can be measured from a negativ e peak recorded the chromatogram. The required parameters for the determina tion of the capacity factor (mu(aq) and mu(me) are the electrophoretic mobi lities of the solutes in the aqueous and the micelle phases, mu(eff) is the effective mobility in the micellar system or in the microemulsion) were me asured by the new micellar and microemulsion electrokinetic chromatography technique. Linear log-log relationships were found between both the micelle -water partition coefficient and the capacity factor and the n-octanol-wate r partition coefficient. (C) 2000 Elsevier Science B.V. All rights reserved .