A new voltammetric strategy for sensitive and selective determination of gallium using cupferron as a complexing agent

Abstract

This article describes a differential pulse adsorptive stripping voltammetric method for the trace determination of gallium in environmental water samples. It is based on the adsorptive deposition of the complex Ga(III)-cupferron at the hanging mercury drop electrode (HMDE) at −0.4 V (versus Ag/AgCl) and its cathodic stripping during the potential scan. The method was optimized as concerns the main electrochemical parameters that affect the voltammetric determination (supporting electrolyte, pH, cupferron concentration, deposition potential and time). The calibration graph is linear from 5 × 10⁻¹⁰ to 5 × 10⁻⁷ mol L⁻¹ with a detection limit calculated as 1.3 × 10⁻¹⁰ mol L⁻¹ for deposition time of 30 s. The influence of interfering substances such as surfactants and humic substances present in the matrices of natural water samples on the Ga(III) signal was examined and a satisfying minimization of these interferences was proposed. The procedure was applied to direct determination of gallium in environmental water samples.

Keywords:

• Gallium; determination
• adsorptive stripping voltammetry
• organic matrix
• environmental water samples