Square-wave Adsorptive Anodic Stripping Voltammetric Determination of Antidiabetic Drug Linagliptin in Pharmaceutical Formulations and Biological Fluids Using a Pencil Graphite Electrode

A simple, sensitive, low-cost, quick and reliable square-wave anodic stripping voltammetric method is described for the determination of the antidiabetic drug Linagliptin (LNG) in pure form, tablets, and spiked human urine and plasma samples. Using a pencil graphite electrode (PGE), cyclic voltammetry (CV) was applied to study the electrochemical behavior of LNG. In a Teorell-Stenhagen buffer (pH 5.5) containing 0.1 M NaClO4 as a supporting electrolyte, the LNG yields an irreversible well-defined oxidation peak at about 1.2 V vs. Ag/AgCl electrode. The various affecting factors, such as the pH, buffer type, supporting electrolyte, accumulation potential, scan rate and accumulation time, were tested and optimized. Also, square-wave adsorptive anodic stripping voltammetric (SWAdASV) studies show that the peak current various linearly over the LNG concentration range of 0.24 - 5.20 mu g mL(-1) (R-2 = 0.9994). The detection and quantification limits were calculated to be 0.10 and 0.33 mu g mL(-1), respectively. The proposed procedure exhibits a good precision, selectivity, and stability and was applied successfully to determine the LNG in pharmaceutical formulations (tablets) and biological fluids (spiked human urine and plasma samples).