Studies on spectrophotometric methods of thallium determination

Eight sensitive methods of spectrophotometric determination of thallium have been studied and compared experimentally. The comparative criteria were: molar absorptivity, colour contrast of the basic reaction, working concentration interval and practical determination limit for thallium, precision of the method (the standard deviation), and selectivity. According to these criteria the best methods of extraction-spectrophotometric determination of thallium are those using Brilliant Green, Crystal Violet, Methyl Violet and Rhodamine B. The sensitivity depends very much on the oxidant used for conversion of Tl(I) into Tl(III). The oxidants suitable for each of the recommended methods are discussed.