A solvent extraction-spectrophotometric determination of bismuth(III) as Tetra-n-butylammonium tetraiodobismuthate.

A solvent extraction-spectrophotometric method has been developed for determination of bismuth in the form of tetra-n-butylammonium tetraiodobismuthate(III). The effects of pH, the concentrations of tetra-n-butylammonium and iodide ions, and the nature and amount of the organic, solvent have been studied. Tetra-n-butylammonium was found to be the most useful cation for extraction of tetraiodobismuthate with chloroform, giving quantitative extraction. The optimum pH is <3, and the extracted species is stable for at least a day at room temperature. Bismuth can be determined at the 10(-5)M level in aqueous solution, the relative standard deviation being 1.7%.