Determination of ultra trace amounts of bismuth in biological and water samples by electrothermal atomic absorption spectrometry (ET-AAS) after cloud point extraction

A new approach for a cloud point extraction electrothermal atomic absorption spectrometric method was used for determining bismuth. The aqueous analyte was acidified with sulfuric acid (pH 3.0-3.5). Triton X-114 was added as a surfactant and dithizone was used as a complexing agent. After phase separation at 50 degrees C based on the cloud point separation of the mixture, the surfactant-rich phase was diluted using tetrahydrofuran (THF). Twenty microliters of the enriched solution and 10 mu l of 0.1% (w/v) Pd(NO3)(2) as chemical modifier were dispersed into the graphite tube and the analyte determined by electrothermal atomic absorption spectrometry. After optimizing extraction conditions and instrumental parameters, a preconcentration factor of 196 was obtained for a sample of only 10 ml. The detection limit was 0.02 ng ml(-1) and the analytical curve was linear for the concentration range of 0.04-0.60 ng ml(-1). Relative standard deviations were < 5%. The method was successfully applied for the extraction and determination of bismuth in tap water and biological samples (urine and hair). (c) 2004 Elsevier B.V. All rights reserved.