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ABSTRACT
A sensor for the adsorptive stripping voltammetric determination of rare earth elements has been developed. The electrochemical procedure is based on the oxidation of the rare earth elements complexed with alizarin complexone at a glassy carbon electrode that was in situ modified with an antimony film, during an anodic scan from –0.2 V to 1.1 V (vs. Ag/AgCl) and deposition potential of –0.1 V (vs. Ag/AgCl). The factors influencing the adsorptive stripping capability were optimised, including the complexing agent concentration, plating concentration of antimony and deposition time. The detection of rare earth elements (La, Ce and Pr) were realised in 0.08 M sodium acetate (pH = 5.8) solution as supporting electrolyte, with 2 × 10−6 M alizarin complexone and 1.0 mg L−1 antimony solution. Under the optimised conditions, a deposition time of 360 s was obtained and a linear response was observed between 1 and 25 µg L−1. The reproducibility of the voltammetric measurements was found to be within 5.0% RSD for 12 replicate measurements of cerium(III) concentration of 5 µg L−1 using the same electrode surface. The detection limits obtained using stripping analysis was 0.06, 0.42 and 0.71 μg L−1 for Ce(III), La(III) and Pr(III), respectively. The developed sensor has been successfully applied for the determination of cerium, lanthanum and praseodymium in municipal tap water samples.
Funding
This work was supported by the Council for Scientific and Industrial Research, Stellenbosch, South Africa. The support provided by the research laboratory at Scientific Services consulting analytical laboratory (Cape Town) and the SensorLab, Chemistry Department, University of the Western Cape, Bellville, South Africa is greatly appreciated. This work was also supported by the National Research Foundation, South Africa.