Sinha, Birendra Chandra and Roy, S K (1980) Complexometric determination of calcium and magnesium in calcite and limestone after selective precipitation of magnesium quinolin-8-olate from a homogeneous solution. The Analyst, 105 (1252). pp. 720-725. ISSN 0003-2654

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Abstract

A simple complexometric method has been developed for the determination of magnesium directly and of calcium by difference at pH � 10, using EDTA in a single aliquot of solution. The method is based on the joint titration of calcium and magnesium with EDTA at pH � 10 and the release of EDTA from the magnesium - EDTA complex by selective precipitation of magnesium quinolin-8-olate from a homogeneous solution with potassium quinolin-8-olate and a known excess of calcium ions at 50-60 °C. The EDTA released is a direct measure of magnesium, and is titrated with calcium solution at 10 °C. The interfering ions, such as zinc, cadmium, manganese and iron are masked by potassium cyanide during the joint titration of calcium and magnesium. Precipitation of the dark coloured iron(III) quinolin-8-olate from the iron(III) - cyanide complex has effectively been prevented by reducing the latter to the iron(II) - cyanide complex with ascorbic acid. Aluminium and titanium, unless present in large amounts (more than 5 mg), have no effect on the method. The method has been successfully applied to the determination of calcium and magnesium in calcite and limestone.

Item Type:	Article
Subjects:	Microstructure and Characterization
Divisions:	UNSPECIFIED
Depositing User:	Bidhan Chaudhuri
Date Deposited:	24 May 2016 10:26
Last Modified:	24 May 2016 10:26
URI:	http://cgcri.csircentral.net/id/eprint/3403

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