UNCLASSIFIED When separating trace quantities from an interfering bulk electroayte, the predominant problem usually involves the effect of co=precivitation of the bulk electrolyte or its incompleteness of sepa ration. Likewise in radio-assay work, the weight of the bulk elect brought down with the carrier added as part of the procedure can le to low recoveries, mainly by self-absorption of the emitted particl by the sample during counting. Ow Figure A=3 shows the effect of increasing amounts of strontium carrier upon the activity. Non=strontium impurities would show the seme effect if they are carried down with the strontium nitrate precipitate since the major impurity is calcium, it is best to know the solubility of Ca(NO3)2 in 75% HNO, so as to insure completeness of removal. This was found to be equivalent to 23.5 grams of CaO per liter of the 75% acids Concentrations above 75% HNOs markedly re- duce the calcium solubility, while cormentrations below may cause too great a solubility loss of strontium, as shown in the factorial reported. An experiment was performed to determine the effect of calcium on the recovery of Sr®°, Solubility measurements indicated that 200 ml] of 75% HNO. would cause a loss of 2.6 mg of Sr or a 13% loss when using 20 mg Sr carrier. Table A=) indicates that the presence of calcium does have a salting effect and that the Sr recovery will be improved by operating close to calcium saturation. If no calcium is present, then a minimum of HNO, should be used. % Saturation 1. 2. 3. he 100 (4.7 g Cad) 75 50 25 c/r & Recovery 1880 91.3 1855 1815 90.0 83.0 1895 91.9 The chemical separation involved in the isolation of Sr®* or y*° from varicus samples may be subject to interference from cther fission products. Table A=5 lists elements mich combine possitle chemical interference with long nelf-life. Their characteristics, along with the perentape of total fission prodyect activity wnich they represent at various times efter detonation, are given in the table along with the corresvonding properties for the strontium anc yttriun fission products. wre SRE UNCLASSIFIED