Sodium dithionite as a selective demasking agent for the complexometric determination of thallium

Autor: Shetty Prakash, Shetty Nityananda A.
Jazyk: angličtina
Rok vydání: 2005
Předmět:
Zdroj: Journal of the Serbian Chemical Society, Vol 70, Iss 11, Pp 1357-1362 (2005)
Druh dokumentu: article
ISSN: 0352-5139
1820-7421
DOI: 10.2298/JSC0511357S
Popis: Sodium dithionite is proposed as a new demasking agent for the rapid and selective complexometric determination of thallium(III). In the presence of diverse metal ions, thallium (III) was first complexed with excess EDTA and the surplus EDTA was then titrated with a standard zinc sulphate solution at pH 5-6 (hexamine buffer) using Xylenol Orange as the indicator. The EDTA equivalent to thallium was then released selectively with sodium dithionite and back titrated with a standard zinc sulphate solution as before. Reproducible and accurate results were obtained in the range 4-100 mg of thallium with a relative error of +-27 % and a coefficient of variation (n = 6) of not more than 0.30 %. The effects of various diverse ions were studied. The method was applied to the determination of thallium in its complexes and in alloys.
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