Selenium is an essential micronutrient for humans and animals. It has antioxidant properties, stimulates the formation of antibodies, and thus enhances the protection of the organism from infections. It is a trace element that is both essential and toxic, with essentiality being confined to a narrow concentration range. Among the known methods for determining trace selenium, stripping voltammetry finds increasing application because of its high sensitivity, simplicity, and inexpensive equipment. A new chemically modified carbon paste electrode (CPE) was constructed and used for rapid, simple, accurate, highly sensitive, and selective determination of selenium(IV) using square wave anodic stripping voltammetry. The electrode was prepared using magnetic nickel zinc ferrite nanocomposite, as the modifier, in CPE. This method is based on formation of mercury selenide and decreasing the current of mercury peak, this followed by square-wave anodic stripping voltammetry. Operational parameters such as pH, deposition potential, and deposition time were optimized. Compared with CPE, the stripping peak currents had a significant increase at the modified electrode. Under the optimal conditions, the limit of detection, based on ten times the background noise, was 0.009 µmol L-1 with a 120s preconcentration. The effects of different cations and anions on the determination of selenium(IV) were investigated. The results indicated that the electrode is highly selective. Furthermore, the present method was applied to the determination of se(IV) in several foodstuff samples.
