Sensitive determination of hydroxylamine by using modified electrode by La2O3–Co3O4 nanocomposite and ionic liquid

Abstract

In the present work, an efficient, fast and sensitive method for the determination of hydroxylamine (HyA) has been developed based on carbon paste electrode (CPE) modified with La2O3/Co3O4 nanocomposite and ionic liquid (LaCo/IL/CPE). The developed method was assessed using cyclic voltammetry, chronoamperometry and differential pulse voltammetry (DPV) methods. The LaCo/IL/CPE sensor showed good response ability and good electrocatalytic activity for HyA. The results showed that, electrochemical oxidation signal of HyA at the surface of LaCo/IL/CPE was 4.8 times the signal at the surface of LaCo/CPE. Also, potential of peak (Ep) of HyA at the surface of LaCo/IL/CPE was 700 mV while at the bare CPE, HyA was not oxidized until the potential reached +1200 mV. The obtained results showed that the oxidation process of HyA at the LaCo/IL/CPE was controlled by diffusion and the average diffusion coefficient for HyA, 2.8 × 10−6 cm2/s was obtained. The experimental conditions such as pH of solution, scan rate and instrumental parameters for DPV were assessed and optimized for electrochemical determination of HyA. Under optimum conditions, a linear response for HyA in the concentration range 0.06–240.0 μM was found, with a detection limit of 3.0 nM. In the final, HyA in different water samples was detected by the standard addition procedure.