Determination of traces of bismuth in water with polyurethane foam thin-layer spectrophotometry

Coloured bismuth iodide complex was sorbed from tap water on to a polyether polyurethane foam thin layer and its absorbance measured at 495 nm and 600 nm against a blank foam in benzene. Net absorbance was correlated with bismuth concentration. Copper and silver ions interfered when present at 10 times the concentration of bismuth. Recoveries of 20 and 45 ug bismuth per 100 ml tap water were, respectively, 107 and 103 per cent.