Determination of rofecoxib, in the presence of its photodegradation product, in pharmaceutical preparations by micellar electrokinetic capillary chromatography

A simple and rapid micellar electrokinetic capillary chromatographic (MEKC) method for analysis of rofecoxib (ROF) and its photodegradation product (PDP) in pharmaceutical preparations has been developed and validated. Analyses were conducted in a fused silica capillary (72 cm effective length, 50 μm i.d.) with a background electrolyte consisting of 25 mmol L^-1 borate buffer at pH 7.0 containing 15 mmol L^-1 sodium dodecyl sulfate (SDS) and 10% acetonitrile (ACN). The separation was performed by voltage-controlled system, applying 30 kV at 30 °C, detecting at 225 nm; injection was hydrodynamic at 50 mbar for 2 s. Nifedipine was used as internal standard (IS). Under the optimum conditions ROF, PDP, and IS were well separated with in 10 min. The method was validated with regard to linearity, limit of detection and quantitation, precision, accuracy, specificity, and robustness. The detection limit of the method was low, 0.8 μg mL^-1, and the linearity range was wide, 2.5 to 125 μg mL^-1. The method was highly efficient-5×10⁵ plates m^-1 for ROF. The method was applied to the tablet form of ROF-containing pharmaceutical preparations. The data were compared with those from the voltammetric method described in literature. No statistically significant difference was found.