Method and apparatus for extraction of strontium from urine

A method for extracting strontium ions from urine, the method comprising the steps of:

• (a) pretreating a sample of urine by acidifying the urine to a pH of less than about 2 with methanesulfonic acid and removing scintillation-interfering materials from the urine;
• (b) loading a known quantity of the pretreated urine onto a preconditioned column of a diphosphonic acid-based ion-exchange resin comprising diphosphonic acid groups and sulfonic acid groups bonded to a particulate polymeric matrix;
• (c) passing a flow of aqueous methanesulfonic acid through the diphosphonic acid-based ion-exchange resin, wherein the flow of aqueous methanesulfonic acid has a concentration and volume sufficient to reduce the concentration of alkali metal ions from the urine eluting from the diphosphonic acid-based ion-exchange resin to about 10 mM or less;
• (d) passing a flow of aqueous nitric acid though the diphosphonic acid-based ion-exchange resin, wherein the flow of aqueous nitric acid has a concentration and volume sufficient to elute at least about 85 mole percent of any strontium ions from the urine off of the diphosphonic acid-based ion-exchange resin;
• (e) directing the flow of aqueous nitric acid containing the strontium ions eluting from the diphosphonic acid-based ion-exchange resin through a column of a preconditioned strontium extraction chromatographic resin comprising a substituted 18-crown-6 crown ether adsorbed onto a porous polymeric support, to concentrate the strontium ions on the strontium extraction chromatographic resin;
• (f) subsequently passing a flow of an aqueous stripping eluent through the strontium extraction chromatographic resin, wherein the stripping eluent comprises water or a dilute acid solution of less that about 0.1 M acid concentration, and has a volume sufficient to elute at least about 85 mole percent of the strontium ions from the strontium extraction chromatographic resin;
• and
• (g) collecting the flow of aqueous stripping eluent containing the strontium ions eluting from the strontium extraction chromatographic resin;
• wherein the diphosphonic acid-based ion-exchange resin is preconditioned with aqueous methanesulfonic acid having a concentration about equal to the concentration of the flow of methanesulfonic acid;
• and the strontium extraction chromatographic resin is preconditioned with aqueous nitric acid having a concentration about equal to the concentration of the flow of nitric acid.