Improvements to arapid method for separating strontium from liquid milk by treatment with a chelating resin and crown ethers

Abstract

In an attempt to improve on a previously reported method¹ for rapidly isolating Sr from liquid milk, the following investigations have been carried out: (1) elution of strontium from a chelating resin with dilute nitric acid, (2) separation of strontium from calcium by extracting from this eluate into chloroform solutions of dicyclohexyl-18-crown-6 (DC18C6), (3) transfer of the strontium into aqueous solution, and (4) removal of barium from this solution by extracting into dichloromethane solutions of 21-crown-7 (21C7). Based on the findings of these studies, a separation scheme was proposed and tested by participating in an interlaboratory comparison on the analysis of⁸⁹Sr and⁹⁰Sr in skimmed milk. The separation scheme requires about 3 hours, provides strontium recoveries greater than 90%, and ensures adequate decontamination factors for the nuclides that occur in milk.