Determination of Bismuth Traces by HG-ICP-OES After Separation by Cloud Point Extraction Using Thiourea and Iodide Mixture

We developed a highly sensitive and selective cloud point extraction methodology for the preconcentration of trace levels of Bi(III) prior to Bi analysis by hydride generation inductively coupled plasma optical emission spectrometry (HG-ICP-OES). Bismuth (III) ions were extracted as ternary mixed iodo/thiourea complexes, at pH 1.0. This extraction was mediated by micelles of non-ionic surfactant (Triton X-114). The optimal extraction and reaction conditions, i.e., pH, reagent and surfactant concentrations, temperature, incubation and centrifuge times, were evaluated and optimized. Under the optimized conditions, linearity was obeyed in the range of 0.10-15 ng mL(-1) of Bi(III) with detection limits of 0.01 and 0.20 ng mL(-1) and preconcentration factors of 500. We examined the matrix effects associated with selected onium complex forming cations [e.g., Cd(II), Hg(II), Pd(II), Fe(III), Ag(I), Pt(IV)] and anions, which may accompany the analyte. The developed method was successfully used to determine the Bi(III) concentrations of synthetic mixtures, and samples of real water, soil, urine, ash coal, pure metals and ointment.