Spectrophotometric method for the determination of thallium(III) with chlorpromazine hydrochloride

A simple, sensitive and rapid spectrophotometric method for the determination of thallium(III) is described, based on the reaction between chlorpromazine hydrochloride and thallium(III) in 4-7 M orthophosphoric acid at room temperature to form a pink species with an absorption maximum at 526 nm. Beer's law is obeyed over the concentration range 0.1-11.5 μg ml-1 of thallium(III), the optimum range being 1.0-10.0 μg ml-1. The Sandell sensitivity of the reaction is 0.0096 μg cm-2 and the molar absorptivity is 2.1 à 104 l mol-1 cm -1. The tolerance limit of the method towards various cations and anions usually associated with thallium has been determined. The method can be used for the determination of thallium in its alloys