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

Abstract

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 μL. 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 μL volume. The content of the loop was then transported by air flow to the graphite furnace and measured. Sample volumes up to 10 mL were pre-concentrated enabling to achieve detection limits down to 0.004 μg 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.