On-line electrochemical pre-concentration of arsenic on a gold coated porous carbon electrode for graphite furnace atomic absorption spectrometry

Trace arsenic was pre-concentrated from water samples in a two-electrode electrochemical flow cell coupled on-line to a graphite furnace atomic absorption spectrometer. The cell comprised a microporous electrode made of gold plated porous carbon material with a void volume of about 20 mu L. The electrodeposition was performed from hydrochloric acid media, the deposit was stripped into diluted nitric acid and the pre-concentrate was transported to a loop of about 60 mu L volume. The content of the loop was then transported by air flow to the graphite furnace and measured. Sample volumes up to 10 mu L were pre-concentrated enabling to achieve detection limits down to 0.004 mu g L-1. The procedure was validated by analyses of CRMs and various water samples. A good agreement with the hydride generation AAS was achieved for all samples.