Synthesis and analytical application of 2,6-dichloroarsenazo as a new chromogenic reagent for bismuth Original Research Article

A new sensitive chromogenic reagent, 2-(2-arsonophenylazo)-7-(2,6-dichlorophenylazo)-1,8-dihydroxynaphthalene-3,6-disulfonic acid (2,6-dichloroarsenazo), has been synthesized and used in the spectrophotometric determination of bismuth. In aqueous 0.6 mol l−1 HClO4, 2,6-dichloroarsenazo can react with bismuth(III) immediately at room temperature to form a deep blue complex with a maximum absorption at 631 nm. The apparent molar absorptivity (ϵ) is 9.87×104 l mol−1 cm−1. Beerʹs law is obeyed over the bismuth concentration range 0–1 μg ml−1. Macroamounts of foreign ions do not interfere. The proposed method has been applied to the determination of bismuth in copper alloys without prior treatment.