Determination of diltiazem in the presence of timolol in human serum samples using a nanoFe3O4@GO modified glassy carbon electrode

Abstract

A new chemically modified electrode was constructed based on a magnetic graphene oxide modified glassy carbon electrode (nanoFe₃O₄@GO-GC). This is for the first time that an electrode was evaluated as an electrochemical sensor for the simultaneous determination of diltiazem and timolol in aqueous solutions. The measurements were carried out by the application of the differential pulse voltammetry method in a phosphate buffer solution with a pH of 6.00. The results revealed that nanoFe₃O₄@GO promotes the rate of oxidation by increasing the peak current. NanoFe₃O₄ loaded: on GO increases the anodic peak currents of diltiazem and timolol on an electrode surface. The electrostatic interaction between the diltiazem and timolol cations and the high electron density of the hydroxyl groups of nanoFe₃O₄@GO led to an increase in the concentration of diltiazem and timolol around the surface of the modified electrode and the peak current increased significantly. The prepared electrode shows voltammetric responses with good selectivity for diltiazem and timolol in optimal conditions, which makes it very suitable for the simultaneous determination of these drugs. The practical analytical utility of the modified electrode was illustrated by the simultaneous determination of diltiazem and timolol in spiked serum samples.