Calcein as an Indicator for the Determination of Total Calcium and Magnesium and Calcium Alone in the Same Aliquot of Milk

Open Access
Publisher Website
Google Scholar
Abstract
The determination of both cations can be performed by back-titration with Cad2 solution in the same aliquot of a diluted milk containing an excess of ethylenediamine-tetraacetate (EDTA). Total Ca and Mg is determined in the pH range 12.0-12.5, whereas Ca alone is measured at pH 13.0-13.5. The values obtained for total Ca and Mg by this method and the Eriochromeblack-T method indicate no significant difference, and added Ca was recovered completely from the milk by this method. Concentrations of phosphates and protein 4 times that present in an average milk and of heavy metals as present in an average milk do not influence results. The method is rapid and reproducible with standard deviation of [plus or minus]0.19% of the measured value for total Ca and Mg and [plus or minus]0.18% of Ca content.