Resumo

NAGARAJA, Padmarajaiah et al. Rapid and Sensitive Spectrophotometric Method for the Determination of the Trace Amount of Thallium (III) in Water and Urine Samples by New Oxidative Coupling Reaction. J. Mex. Chem. Soc [online]. 2009, vol.53, n.4, pp.201-208. ISSN 1870-249X.

A very simple, sensitive and fairly selective direct spectrophotometric method is presented for the rapid determination of thallium(III) at trace level. The method is based on the oxidation of 2-hydrazono-3-methyl-2,3-dihydrobenzo[d]thiazole hydrochloride (MBTH) by thallium(III) in phosphoric acid medium to form a diazonium cation, which couples immediately with 10,11-dihydro-5H-dibenzo[b,f]azepme (IDB) at room temperature giving a blue colored species having a maximum absorption at 660 nm. The reaction conditions and other important analytical parameters were optimized. The calibration curve was found to be linear over the range of 0.1-4 µg/mL with molar absorptivity of 4.5 × 10⁴ L mol^- cm^-1 and Sandell's sensitivity of 0.00454 µg cm^-2. The relative standard deviation and limit of detection have been found to be 0.58% and 0.0147 µg/mL respectively. Almost all common anions and cations are found not to interfering in matrix level of the analytical process. The method has been successfully applied for the determination of thallium(III) in synthetic standard mixtures, water and human urine samples. The performance of proposed method was evaluated in terms of student's t-test and variance ratio F-test, to find out the significance of proposed method over the reported methods.

Palavras-chave : Thallium determination; MBTH; IDB; Spectrophotometry; Water samples; Urine samples.

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