A New Approach on Sensitive Assay of Adefovir in Pharmaceutical and Biological Fluid Samples Using Polypyrrole Modified Glassy Carbon Electrode

In this work, a polypyrrole modified glassy carbon electrode (PPy/GCE) was used as a promising electrode for the electrochemical sensing of adefovir (ADV). The electrooxidation behavior of ADV was studied using cyclic voltammetry (CV), square wave (SWV) and differential pulse voltammetric (DPV) techniques. The oxidation mechanism of drug on PPy/GCE was proposed using the obtained data and discussed as details. The effect of the chemical and instrumental variables was carried out to select the optimum experimental conditions. The ADV electrooxidation was found to be diffusion-controlled process in 0.1 M H2SO4 (pH 1.0) solution. The electrochemical detection of ADV was studied using DPV technique where the anodic peak of ADV was measured as an analytical signal. The analytical plot was linear between 0.25 and 50.0 mu M with a good determination coefficient of 0.998 in bulk solution. The detection limit of ADV was obtained as 3.10 nM. Moreover, the fabricated sensor was applied to determine ADV in human serum over the concentration range 0.25-5.00 mu M (R-2 = 0.997) with the detection limit 0.06 mu M, whereas in urine 0.25-7.5 mu M (R-2 = 0.996) with the detection limit 0.04 mu M. The electroanalysis of ADV in tablet dosage forms was also verified with satisfactory recovery values.