Study of electrochemical properties of gold-bismuth electrodes. Applications in voltammetric detection of sub nM copper, lead and mercury in natural waters

Electrochemical properties for different gold-bismuth alloy electrodes have been evaluated, end tested for use in voltammetric analyses, especially for detection of copper, lead and mercury. Increased overpotential towards the hydrogen overvoltage reaction (HER) was found as function of increased bismuth amount in the gold. A study of oxidizing products by cyclic voltammetry (CV) in NaOH solution was also carried out to studding formation of different oxide products on the alloy surface. Differential pulse anodic stripping voltammetry (DPASV) was used to measure the actual metals, and good linearity was found for all metals (r2=0.95) in the range of 0.1 to 10 ppb with 600 to 1200 s plating time. Also, peak potentials for copper, lead and mercury were studied as a function of amount bismuth present in the alloy. The analytical use and stability over time of such gold-bismuth alloy electrodes was evaluated in natural water including for use in speciation studies together with ICP-MS measurements in real samples of run-of water from Spitzbergen.