RADIOMETRIC METHODS FOR THE DETERMINATION OF MAGNESIUM AND CALCIUM IN PORTLAND CEMENT

Radiometric methods of analysis for magnesium and calcium have been developed as part of a program for the U. S. Atomic Energy Commission. Office of Isotopes Development, which are applicable to the determination of these elements in portland cement Both methods employ, as a precipitant, a standard solution of (NH/sub 4/)/sub 2/HPO/sub 4/ labeled with phosphorus-32. In the presence of NH/ sub 4/OH, this reagent precipitate; MgNH/sub 4/PO/sub 4/ or Ca/sub 3/(PO/sub 4/)/ sub 2/ from a solution of magnesium or calcium ions. The reduction in the radioactivity level of the labeled phosphate solution after precipitation serves as a measure of the phosphate reacted and thus a measure of the quantity of magnesium or calcium present. Studies have been made of the effects of reagent concentration, NH/sub 4/OH concentration, and other experimental variables. The interference of other elements present normally in portland cement and its raw materials has been determined. The concentration ranges for highest accuracy have been found to be 5 to 15 mg of MgO per 100 ml and 15 to 30 mg of CaO per 50 ml. (auth