A simultaneous assay method using capillary zone electrophoresis for a fixed dose combination of vildagliptin and metformin hydrochloride in coated tablets

In the present study, a quick and reliable validated capillary zone electrophoresis (CZE) method was established for the simultaneous determination of vildagliptin (VLG) and metformin hydrochloride (MET) in pharmaceutical dosage form. Successful separation of the drugs by the CZE method was achieved in a fused silica capillary by applying a potential of 25 kV (positive polarity) and hydrodynamic injection by 50 mbar for 5 s. The selected running buffer consisted of 25 mM sodium tetraborate decahydrate solution (array pH 9.0) with UV/photodiode (PDA) detection at 207 nm and 250 nm for VLG and MET respectively. Specificity, linearity, precision, accuracy, limit of detection and limit of quantitation and robustness were established for VLG and MET in accordance with International Conference on Harmonization (ICH) guidelines. The specificity and stability-indicating capability of the method was established by enforced degradation studies combined with peak purity assessment using PDA detection. Electrophoretic separation was obtained within 10 min and the method was linear in the range of 30-60 mu g mL super(-1) and 300-600 mu g mL super(-1) for VLG and MET, respectively (R super(2) > 0.9980). Precision of the method was reflected by RSD lower than 2.95% and accuracy results around 100% for both VLG and MET measurement. Moreover, the Plackett-Burman experimental design was used to evaluate robustness, producing results within the acceptable range.