Titration of Calcium and Magnesium in Wine with Ethylenediamine Tetraacetate

Abstract

The method of preparing wine samples for the determination of total calcium and magnesium yields satisfactory results.

The presence of 2-hydroxy-1-(2-hydroxy-4-sulfo-1-naphthylazo)-3-naphthoic acid reagent in the solution did not influence the color change of the Eriochrome Black T indicator used in the magnesium determination. The color change during the magnesium determination was particularly sharp if the solution temperature was maintained above 80°C during the titration.

Interference of iron, aluminum and manganese could be masked with triethanolamine while 2,3-dimercaptopropanol could be used to mask interference of lead, bismuth, zinc, cadmium, mercury, silver, arsenic, tin and antimony. When triethanolamine was used as masking agent in the magnesium determination af pH 10, in some cases a yellow color was produced. The solution could be decolorized by the addition of small amounts of potassium hydroxide, however, without impairing the accuracy of the determination.

The titrimetric procedure presented is of accuracy comparable to that of classical methods for the ctefermination of calcium and magnesium and the entire procedure requires much less time.