Selective and sensitive determination of Cd(II) ions in various samples using a novel modified carbon paste electrode

Based on the highly toxic effects of Cd(II) on the aquatic environment and the human health, identification and evaluation of such pollutants is required. Efficient and economic electrodes for sensitive and selective detection of this element are very important. In this study, carbon paste electrode (CPE) modified with lanthanum tungstate ion exchanger was assembled for potentiometric assay of Cd(II) ions. The prepared sensor exhibited a Nernstian response for Cd(II) within a wide working range of 8 × 10⁻⁸–1 × 10⁻¹ mol L⁻¹, with a slope of 29.4 ± 0.12 mV/decade. It has been specified by a low detection limit of 8 × 10⁻⁸ mol L⁻¹ and a short response time of ~ 5 s and can be utilized efficiently up to 22 weeks without any significant errors in the potential determination. The standard electrode potentials, E°, and the isothermal temperature coefficient (dE°/dt) of the sensor were estimated at various temperatures. The obtained results indicated that the nominated electrode has efficient performance to estimate Cd(II) in its pure solutions and other various real samples (river water, plant foodstuff, industrial wastewater, nickel cadmium battery, and fish tissue samples).