Preconcentration of thallium with 2-nitroso-I-naphthol-4-sulphonic acidtetradecyldimethy lbenzylammonium chloride on microcrystalline naphthalene and its determination by DPP

913-916Thallium(l) is quantitatively retained as 2-nitrosol-naphthol-4 -suIphonic acid-tetradecyldimethylbenzyl-ammonium  chloride on microcrystalline naphthalene in the pH range 10-11.5 from its aqueous solution. After adsorption, the metal is desorbed with 10 ml of 1M HCI and determined by differential pulse polarography. The detection limit is 0.2 mg/ml (signal to noise ratio = 2) and the linearity is maintained in the concentration range 0.4-180 mg/10 ml of the final solution (r = 0.9995: rsd = 0.95%). The degree of revcrsibility has also been examined. Various parameters such as the effect of pH, concentrations of aqueous phase, HCl, reagent and naphthalene, shaking time and interference of a number of metal ions and anions on the determination of thallium (I) have been studied to optimize the conditions. The method has been successfully applied for estimation of Tl(l) in environmental and biological samples