Preparation of TiO.sub.2 Nanoparticles-Au Nanoparticles-chitosan Nanocomposite Modified Pencil Graphite Electrode: Application for Electrochemical Measurement of Amlodipine in Biological and Pharmaceutical Samples

The nanocomposite of TiO.sub.2 nanoparticles, Au nanoparticles and chitosan was explored for the modification of the pencil graphite electrode surface (TiO.sub.2NPs-AuNPs-Chit/PGE). Electrochemical impedance spectroscopy and scanning electron microscopy techniques were used to study the interfacial properties and surface morphology of the modified electrode, respectively. This modified electrode was applied for electrochemical determination of anti-blood pressure drug amlodipine (AML). Electrochemical behavior of AML at the modified electrode was investigated by cyclic voltammetry, chronoamperometry and differential pulse voltammetry techniques. Cyclic voltammetry experiments showed that the oxidation peak current of AML increased and its oxidation overpotential decreased at the modified electrode in comparison to the bare electrode. This observation indicated the electrocatalytic activity of the modified electrode toward AML. Parameters affecting the electrochemical performance of the modified electrode toward AML were optimized. Using differential pulse voltammetry technique under optimized conditions revealed that the oxidation peak currents of AML increased linearly with increasing AML concentration over the range of 0.04-2.8 [micro]M. The detection limit of the method was calculated as 0.015 [micro]M (S/N = 3). Finally, the developed electrode was utilized for the determination of AML in some biological (human serum and urine) and pharmaceutical samples and satisfactory recoveries were obtained.