Spectrophotometric Determination of Bismuth with 2-(2-Thiazolylazo)- 4-methylphenol in the Presence of Zephiramine

Abstract

The method of spectrophotometric determination of bismuth with 2- (2-thiazolylazo)-4- methylphenol (TAC) in the presence of Zephiramine was studied. The color of bismuth complex is darkish-green. The absorbance at 596 nm (absorption maximum) was constant in the pH range from 6.0 to 7.0 and stable for at least 3 hours. Up to the concentration of 3 pgImi of bismuth, the solution obeyed Beer's law. The molar ext- inction coefficient of the complex at 596 nm was 3.44x10' iol-' m-i and the sensitivity for bismuth was 6.07 X 10-8, ugfcm² per 0.001 of absorbance. The composition ratio of bismuth to TAC in the complex was confirmed to be 1: 4 by the continuous variation method. A number of ions which interfere with the determination could be masked by the addition of various masking agents. Co²⁺, Cu²⁺, Fe2+, Ni²⁺ and Th4+, interfered with the determination of bismuth with positive errors, while Crs+, Nb", Sn2+, TO+, citrate, and tartrate ions with negative errors.