Determination of Ofloxacin Enantiomers in Pharmaceutical Formulations by Capillary Electrophoresis

Abstract

A capillary electrophoretic method for the separation of the enantiomers of ofloxacin using carboxymethyl‐β‐cyclodextrin (CM‐β‐CD) as chiral selector is described. The effect of the type of cyclodextrin and its concentration, buffer concentration, and its pH, as well as instrumental parameters, such as applied voltage and temperature were systematically studied. The highest resolution of ofloxacin enantiomers obtained was around 2.8. This was achieved using Tris‐citrate buffer (pH 4.5) that contained 3 mg mL⁻¹ CM‐β‐CD and using UV detection (254 nm), applied voltage (12 kV), and capillary temperature of 25°C. Acceptable validation criteria for selectivity, precision, linearity, limit of detection, and quantitation were also included. Recoveries between 98.3–103.4% were obtained when the method was used to determine the enantiomers of ofloxacin that were spiked to placebos. The proposed method is fast, sensitive, inexpensive, and its usefulness was demonstrated for the analysis of five pharmaceutical preparations, two of which just contained the S‐ofloxacin while the other three contained both isomers as racemic mixtures.

Keywords:

• Ofloxacin
• Enantiomers
• Capillary electrophoresis
• Pharmaceutical formulations

Acknowledgments

Financial support of the work by the Universiti Sains Malaysia via Short Term and SAGA research grant schemes are gratefully acknowledged. One of us (Abdalla A. Elbashir) is also indebted to the Institute of Postgraduate Studies, USM, for awarding a graduate research assistantship.