Capillary electrophoretic behaviour and determination of enoxacin in pharmaceutical preparations and human serum

Abstract

A validated capillary electrophoretic method with UV detection is described for the determination of enoxacin [ENX] in pharmaceutical preparation and human serum. The experiments were carried out in a fused-silica capillary (ID=75 µm, total 88 cm, effective 58 cm length) using a 20 mM borate buffer at pH 8.6, applying a potential of 30 kV, 1 s of injection. Acetylpipedimic acid was used as an internal standard (IS) and the detection was performed at 265 nm. The tM±RSD% of ENX and IS were 4.8±0.9 and 5.5±1.2 minutes, respectively. A well-correlated calibration equation was obtained in the range of 3.1x10-6-3.1x10-5 M ENX. Limit of detection (LOD) was 3.5x10-6 M (S/N = 3). A modified reversed-phase HPLC was also conducted using a C-18 ODS column for the analysis of ENX to compare to its applicability with the CE method. An isocratic elution was performed using a mobile phase of 10 mM phosphate buffer (pH 4.0) and acetonitrile (85:15;v/v) detecting at 260 nm. The determination of ENX in the pharmaceutical tablet formulation was carried out by both methods and the results of a single tablet (as mg with their RSD% values) was found to be 421.4±1.0 and 415.9±0.9 by CE and HPLC, respectively. ENX analysis was also performed by a standard addition method in serum, and the recoveries were found to be 89.7±0.6 (CE) and 78.8+4.9 (HPLC). It was concluded that capillary electrophoresis for the determination of ENX is a promising method for routine analysis and pharmacokinetic and bioavailability studies.