1981 Volume 30 Issue 12 Pages 800-803
The extraction-spectrophotometric determination of bismuth with Bismuthiol II in the presence of acetic acid was studied. Bismuth(III) was extracted into chloroform as a ternary complex containing acetic acid. A constant absorbance at 335 nm (absorption maximum) is obtained in the pH range from 3.5 to 5.0, and the extraction efficiency is larger than 99 % in this pH range. Beer's law is obeyed up to 370 μg of bismuth in 10 ml chloroform. The molar extinction coefficient was 4.5 × 104 l mol-1 cm-1, the sensitivity being 4.65 × 10-3 μg/cm2 per 0.001 of absorbance. The composition ratio of the ternary bismuth complex extracted into chloroform was comfirmed to be 1:3:2 (Bi: Bismuthiol II: acetic acid). The recommended procedure is as follows: Take (1040) ml of sample solution containing less than 100 μg of bismuth into a beaker. Add 2 ml of a acetic acid (1+9), and adjust the pH to 4.5 with hydrochloric acid or ammonia. Add 2 ml of 0.1 % Bismuthiol II solution, and dilute to 50 ml with water. Then extract the bismuth complex with 10 ml chloroform by shaking for 3 min. Measure the absorbance at 335 nm against the reagent blank as the reference. Ag(I), Au(III), Fe(III), and Hg(II) which interfere with the determination could be masked by ascorbic acid, but copper(II) interferes significantly with the determination.
