In this study, a simple and highly sensitive sensor for the determination of omeprazole based on magnetic nickel zinc ferrite nanocomposite (Ni 0.5 Zn 0.5 Fe 2 O 4 ), as the modifier, on multi-walled carbon nanotubes (MWCNTs) modified glassy carbon electrode (Ni 0.5 Zn 0.5 Fe 2 O 4 /MWCNTs- GCE) is reported. Omeprazole (OMZ), is a benzimidazole derivative which acts as proton pump inhibitor (PPI). It is a drug used for the effective treatment of gastric and duodenal (peptic) ulcers, reflux esophagitis, Zollinger-Allison syndrome, and other gastrointestinal conditions where gastric acid reduction is beneficial, and has found worldwide popularity over the past decade. Electrochemical methods have confirmed to be highly sensitive for the analysis of drugs in pharmaceutical formulations and also in human body fluids. These methods are simple and versatile due to their advantages such as cheap instrumentation, quick response time, high sensitivity and wide linearity. Scanning electron microscopy (SEM) along with energy dispersive X-ray spectroscopy (EDS), cyclic voltammetry (CV) and differential pulse voltammetry (DPV) were used to characterize the nanostructure and performance of the sensor and the results were compared with those obtained at the multi-walled carbon nanotube modified glassy carbon electrode (MWCNTs/GCE). Under the optimized experimental conditions omeprazole gave linear response over the range of 0.03-100 µmol L -1 . The detection limit was found to be 0.017 µmol L -1 . The effect of common interferences on the current response of omeprazole was investigated. The practical application of the modified electrode was demonstrated by measuring the concentration of omeprazole in plasma and pharmaceutical samples. This revealed that the Ni 0.5 Zn 0.5 Fe 2 O 4 /MWCNTs-GCE shows excellent analytical performance for the determination of omeprazole in terms of a very low detection limit, high sensitivity, very good accuracy, repeatability and reproducibility.
