Ultratrace Determination of Indium in Natural Water by Adsorptive Stripping Voltammetry in the Presence of Cupferron as a Complexing Agent

A novel and highly sensitive adsorptive voltammetric procedure for direct determination of In(III) in natural water samples was introduced. The method is based on cathodic adsorptive stripping voltammetry of the In(III)-cupferron complex at a renewable mercury film silver based electrode (Hg(Ag) FE). Experimental conditions were established and included: 0.1 mol L-1 acetate buffer (pH = 5.5), 5 x 10(-5) mol L-1 cupferron, accumulation potential 0 V. The calibration graph was linear from 5 x 10(-10) mol L-1 to 2 x 10(-8) mol L-1 with the correlation coefficient of 0.9993. Limit of detection (LOD) and limit of quantification (LOQ) for preconcentration time of 30 s were 1.5 x 10(-10) mol L-1 and 5 x 10(-10) mol L-1, respectively. The interference of surface active substances and humic substances on the indium voltammetric signal was precisely examined, and effectively minimalized. The application of the procedure to the analysis of natural water samples was validated by the determination of indium in certificate reference materials SPS-WW1 Wastewater and SPS-SW1 Surface Water, river water, rain water and tap water. (C) 2016 The Electrochemical Society. All rights reserved.