A Plan for the Rapid Determination of the Major Cations in Milk

Abstract

In studying the effects of the major cations present in milk upon its properties, a routine analytical procedure that is rapid and accurate is needed. The time-consuming steps involved in eliminating interfering ions in the usual chemical methods for sodium Keirs and Speck However, magnesium and calcium can be determined rapidly with ethylenediamine tetraacetate as the titrating reagent and suitable indicators by the method of Schwarzenbach et al. ( Both this method and the flame-photometric determination of calcium require ashing or wet digestion to remove the interfering organic matter and subsequent treatment to remove the phosphates and other interfering ions. However, Jenness (6') in applying the method of Schwarzenbach to milk found that a milk sermn prepared by acid precipitation followed by treatment with an anion-exchange resin in the acetate form could be analyzed directly for calcium and magnesium and was superior to the other methods of sample preparation, since it requires less time than ashing and less exchange resin than wet digestion.