Ion-exchanger colorimetry-IV microdetermination of bismuth in water

Ion-exchanger colorimetry for the microdetermination of bismuth(III) in water samples is described. The yellow bismuth-iodide complexes are specifically sorbed and concentrated on an anion-exchange resin in the sulphate form. The resin-phase absorbances at 492 and 700 nm are measured directly. Bismuth in the ppb-ppm range can be determined without interference, except in presence of a large amount of copper(II), silver(I) and lead(II). The detection limit is 6.4 x 10(-9)M, i.e., 1.3 ppb. The distribution ratio is larger than 10(7). It is, therefore, possible to enhance the sensitivity by increasing the sample volume. The method is useful for the determination of bismuth in natural waters and industrial effluents.