Voltammetric determination of vildagliptin in a pharmaceutical formulation

Purpose: To determine vildagliptin concentration in a pharmaceutical formulation using voltammetric analysis techniques, and optimize the parameters affecting the techniques. Method: Four types of voltammetry techniques, including cyclic voltammetry (CV), differential pulse voltammetry (DPV), square wave voltammetry (SWV), and linear sweep voltammetry (LSV), were employed to measure vildagliptin. Platinum (Pt) and glassy carbon (GC) were used as working electrodes, while KNO3 (1 M) and phosphate buffer (NaH2PO4/H3PO4) pH 6.8 were used to study optimal voltammetric analysis conditions. Results: CV results indicate that vildagliptin is electroactive and exhibits irreversible redox cycles while LSV results showed an oxidation peak current around 1.35 V that has high sensitivity and a linear standard regression line correlation coefficient of 0.9995. In addition, LSV results showed that vildagliptin has a lower limit of detection of similar to 0.241 mM and a limit of quantification of similar to 0.802 mM. Finally, the results show that vildagliptin has an acceptable level of recovery of 104.1 % and a relative standard deviation of 0.52 % for the commercially available vildagliptin tablets used in this study. Conclusion: The accuracy and precision of all applied voltammetric techniques for vildagliptin analysis are within accepted limits stipulated in pharmaceutical analysis quality control guidelines. The recommended method for vildagliptin analysis is LSV with Pt as the working electrode and KNO3 (1 M) as the supporting electrolyte.