Application of micellar electrokinetic capillary chromatography for the determination of nifedipine and its degradation product in pharmaceutical preparations

A simple and rapid micellar electrokinetic capillary chromatographic (MEKC) method for the analysis of nifedipine (NIF) and its degradation product was developed and validated. The compounds were separated using a 100 mM borate buffer at pH 9.0 containing 15 mM sodium dodecyl sulphate (SDS) and 25% acetonitrile, applied voltage of 30 kV, at working temperature 30degreesC and fused silica capillary of 72 cm effective length. Hydrodynamic injection (50 mbar) was applied for 3 s. The detection wavelength was set at 236 nm. Nimodipine was used as internal standard (IS) to compensate for minor fluctuations of migration times. Under the optimum conditions NIF, nitroso analog of dehydronifedipine (NDNIF) (degradation product exposed to sunlight) and IS were well separated with in 9 min. The method was validated with respect to linearity range, limit of detection and quantitation, precision, accuracy, specificity, ruggedness, and robustness. The method exhibited low limit of detection as 0.5 mug mL(-1), wide linearity range of 2-100 mug mL(-1) and high efficiency 1 x 10(5) N/m for NIF. The method was applied to the tablet form of NIF containing pharmaceutical preparations. The data were compared with that of the differential pulse polarographic method mentioned in literature. No significant difference was found statistically.