Fast separation of terbinafine and eight of its metabolites by capillary electrophoresis

A rapid and simple capillary zone electrophoresis (CZE) method for the dete rmination of terbinafine and eight of its main metabolites after incubation with rat hepatic S9 fraction was developed. The effect of the concentratio n and type of the running electrolyte as well as of the addition of an orga nic solvent were studied with emphasis on selectivity and sensitivity. All nine components obtained (unmetabolized terbinafine and up to eight of its metabolites) are baseline resolved in less than 4 minutes using a 0.05 M ph osphate buffer (pH 2.2) without additives, after a solid-phase clean-up pro cedure of these in-vitro samples. In addition, under the conditions describ ed, no endogenous components of the sample interfere at the detection wavel ength chosen. After optimization of the separation conditions, some analyti cal characteristics of the developed CZE method were investigated. A limit of detection of only 0.08 mug/mL was obtained for terbinafine using a stand ard solution. Finally, the use of on-line CZE/ diode array detection enable d to identify tentatively the presence of unmetabolized parent terbinafine and its metabolites in the mixture of nine components separated.