Abstract
In this work, an accurate, high sensitive and economy electrochemical sensor based on a carbon paste electrode provided by copper oxide nanoparticles (CuO-NP/CPE) was constructed. CuO-NP were obtained from the recycling of copper waste wires and analyzed using SEM and XRD measurements. The handmade electrode was used in actual pharmaceutical formulations for the determination of theophylline (TP). Using cyclic voltammetry (CV) and linear sweep voltammetry (LSV) methods, the output accuracy of the sensor against TP was explored. Different experimental conditions have been studied, such as different supporting electrolytes, pH, and scan rate. The results showed that while only one peak of oxidation was observed at 1.16 V, no reduction peaks were observed. The improved CuO-NP/CPE sensor showed supreme analytical rendering towards TP, with an anodic peak current rising by 4 mu A compared to the unimproved CPE. The peak of oxidation current was linearly proportional to the concentration of TP from 4.0 to 70.0 nM, and the detection limit was determined to be 1.2 nM, which, relative to previous research using the same technology, was considered the lowest value ever. In addition, handmade CuO-NP/CPE showed high selectivity, stability, and good reproducibility in the presence of any interference. Therefore, it has been successfully used in actual pharmaceutical samples to assess TP. The data showed that the adjusted sensor significantly improved the detection of TP as well as accelerated the process of charge transfer on its surface with efficient reusability for eight successive measurements at 4 x 10(-4) M of TP.