University of North Florida
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Stuart Chalk, Ph.D.
Department of Chemistry
University of North Florida
Phone: 1-904-620-1938
Fax: 1-904-620-3535
Website: @unf

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Classification: Geological -> rock -> limestone

Citations 1

"Determination Of Calcium And Magnesium In Limestone And Dolomite By Enthalpimetric Flow Injection Analysis"
Talanta 1987 Volume 34, Issue 6 Pages 543-546
Walace A. de Oliveira and Afonso S. Mendes

Abstract: A 1-g sample (100 mesh, dried at 100°C for 1 h) was moistened with water, and 6 M HCl and concentrated HNO3 were added. The mixture was evaporated, the residue was dissolved in water, the solution was filtered and the filtrate was diluted to 50 mL. For the determination of Ca, a 5 mL aliquot was mixed with 10% hydroxylammonium chloride solution, NH4Cl buffer (pH 10) and 40% triethanolamine solution containing 6% of KCN. The solution was fed into a flow manifold with the buffer solution as carrier and 0.2 M MgEDTA in buffer as reagent. A similar procedure was used in the determination of Mg except that a borate buffer (pH 9.2) was used and the reagent was 0.2 M Na2EDTA. The Ca concentration. was calculated by measuring the heat evolved in the exchange reaction with MgEDTA. The enthalpimetric signal from complexation with Na2EDTA gave the sum of Ca and Mg, from which the Mg concentration. was calculated. Analysis of various limestone and dolomite samples indicated an error of ~0.3% of MgO or CaO. A sampling rate of 100 h-1 was achieved.
Calcium Magnesium Enthalpimetry Complexation