In this paper, an activated bismuth layer formed in situ on a solid bismuth microelectrode, used as a working electrode for the electrochemical sensitive determination of Ga(III), based on anodic stripping voltammetry (ASV) is discussed. The new electrode significantly enhances the sensitivity in the ASV determination of Ga(III) and exhibits superior performance in comparison to a bismuth film electrode prepared on a glassy carbon disc. The experimental variables, such as the potential and time of solid-bismuth-microelectrode activation, the composition of the supporting electrolyte, and the influence of possible interferences on the Ga(III) signal response, were tested. The most favorable values were selected (pH = 4.6; acetate buffer; activation potential/time: -1.8 V/6 s and -1.4 V/60 s). In the optimized conditions, the peak current was found to be proportional to the concentration of Ga(III) over the range from 2 × 10-8 to 2 × 10-6 mol L-1 with R = 0.993. The limit of detection (LOD) was 7 × 10-9 mol L-1. Finally, the proposed method was successfully applied for gallium determination in certified reference waters, such as surface water and waste water, as well as tap and river water samples. The water samples were analyzed without any pretreatment and recovery values from 92.4 to 105.5% were obtained.
Keywords: activated bismuth layer formed in situ on a solid bismuth microelectrode; electrochemical measurement; gallium; stripping voltammetry.