Cloud-Point Extraction and Spectrophotometric Determination of Trace Quantities of Bismuth in Environmental Water and Biological Samples

A cloud-point extraction (CPE) process using the nonionic surfactant Triton X-114 to extract bismuth from aqueous solutions was investigated. The method is based on the complexation reaction of Bi(III) with 4-(2-benzothiazolylazo)2,2′-biphenyldiol (BTABD) and micelle-mediated extraction of the complex. The optimal extraction and reaction conditions (e.g., pH, reagent concentration, surfactant concentration, and effect of time) were studied. The analytical characteristics of the method (e.g., linear range, molar absorptivity, Sandell sensitivity, optimum Ringbom concentration ranges, limits of detection and quantification, preconcentration factor, and improvement factors) were obtained. Linearity was obeyed in the range of 2.50–85.0 ng mL−1 of Bi(III) ion. The detection limit of the method was 0.75 ng mL−1 of Bi(III) ion. The interference effect of some anions and cations was also tested. The method was applied to the determination of bismuth in environmental water, human hair, and urine samples.