Electrooxidation and determination of etidronate using copper nanoparticles and microparticles-modified carbon paste electrodes

Abstract

The electrochemical behavior and determination of a bisphosphonate drug, sodium etidronate, on three different copper-based electrodes: polycrystalline copper electrode (CE) and copper microparticles- (m-CPE) and copper nanoparticles (n-CPE)-modified carbon paste electrodes was investigated. In the voltammograms recorded using CE, one anodic peak was appeared while, both m-CPE and n-CPE represented two anodic oxidation peaks. The anodic current density at 610 mV for n-CPE is >5 times higher that of m-CPE. This was related to the nanosize effect of copper nanoparticles. The anodic currents were related to the electrocatalytic oxidation of etidronate via the electrogenerated active species of Cu(III) in an EC' mechanism. The catalytic rate constant for the oxidation process and the diffusion coefficient of etidronate were obtained as 8.9×10³ cm³ mol-1 s-1 and 1.55×10-6 cm² s-1, respectively. A sensitive and time-saving sensing procedure was developed for the analysis of etidronate, and the corresponding analytical parameters were reported. Etidronate was determined with a limit of detection of 10.57 μmol L-1 with a linear range of 200-2538 μmol L-1. Accuracy was also checked by recovery test on spiked samples. The proposed amperometric method was applied to the analysis of commercial pharmaceutical tablets and the results were in good agreement with the declared values.