The bismuth bulk annular band electrode - a new voltammetric sensor for Al(III) traces determination

摘要

This work presents for the first time an indirect, voltammetric determination of Al(III) traces as Al-Alizarin S complex, using the environmental friendly bismuth bulk annular band electrode (BiABE). These researches were aimed at replacing the typically used sensors, based on highly toxic mercury. The differential pulse stripping voltammetric measurements were realized in relatively simple electrolyte i.e. 0.075 M ammonia buffer of restrictively controlled pH equal to 9.2. It was found, that the electrode process is irreversible and controlled by both, diffusion and adsorption phenomena. The calibration graph was linear from 4 to 40 mu g L-1 with sensitivity of 0.20 mu A/mu g L-1, and repeatability below 2.1%. In the Al concentration range from 0.2 to 2 mu g L-1 sensitivity increased to 0.54 mu A/mu g L-1 with limit of detection 0.015 mu g L(-1 )and repeatability below 3.1%. The optimal preconcentration time was 20 s. It was also demonstrated that conditioning of the solid electrode surface leads to considerable improvement of analytical parameters. The proposed method accuracy was verified using two certified reference materials of complex composition, i.e. tea leaves and surface water, in which Al(III) was determined with recoveries 99.72% and 101.86%, respectively. Additionally, due to relatively low reduction potential equal to -790 my, this sensor offers wide application capabilities regarding quantitative determination of Al(III) traces. (C) 2019 Published by Elsevier B.V.