Adsorptive Voltammetric Studies on the Cerium(III)–Alizarin Complexon Complex at a Carbon Paste Electrode

Voltammetric and Spectroscopic Determination of Rare Earth Elements in Fresh and Surface Water Samples

The increasing demand for rare earth elements in green technology, electronic components, petroleum refining, and agricultural activities has resulted in their scattering and accumulation in the environment. This study determined cerium, lanthanum and praseodymium in environmental water samples with the help of adsorptive differential pulse stripping voltammetry (AdDPSV) and inductive coupled plasma-optical emission spectroscopy (ICP-OES). A comparison of the results of these two analytical techniques was also made. The accuracy and precision of the methods were evaluated by spiking water samples with a known amount of REEs. The detection limit obtained for the stripping analysis was 0.10 μg/L for Ce(III), and 2.10 μg/L for combined La(III) and Pr(III). The spectroscopic method of determination by ICP-OES was applied to the same samples to evaluate the effectiveness of the voltammetry procedure. The ICP-OES detection limit obtained was 2.45, 3.12 and 3.90 μg/L for Ce(III), La(III) and Pr(III), respectively. The results obtained from the two techniques showed low detection limits in voltammetry; the ICP-OES method achieved better simultaneous analysis. This sensor has been successfully applied for the determination of cerium, lanthanum, and praseodymium in environmental water samples, offering good results.

Antimony film sensor for sensitive rare earth metal analysis in environmental samples

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.

Carbon paste electrodes in the new millennium

In this review (with 500 refs), both electrochemistry and electroanalysis with carbon paste-based electrodes, sensors, and detectors are of interest, when attention is focused on the research activities in the years of new millennium. Concerned are all important aspects of the field, from fundamental investigations with carbon paste as the electrode material, via laboratory examination of the first electrode prototypes, basic and advanced studies of various electrode processes and other phenomena, up to practical applications to the determination of inorganic ions, complexes, and molecules. The latter is presented in a series of extensive tables, offering a nearly complete survey of methods published within the period of 2001–2008. Finally, the latest trends and outstanding achievements are also outlined and future prospects given.