Summary of Method

Strontium is separated and concentrated from 100mL urine samples using calcium phosphate precipitation. An optional wet-ashing step with HNO3-H2O2 destroys residual organic material. The precipitate or wet-ashed residue is dissolved in nitric acid and aluminum nitrate. Strontium is then separated from matrix impurities and potentially interfering radionuclides in the sample using a 2mL cartridge of Eichrom Sr Resin. Radiostrontium is measured on a low background gas flow proportional counter or liquid scintillation counter. Chemical yield of strontium
is determined by gravimetric recovery of stable strontium or ICP-AES measurement. Typical chemical recovery of strontium is >80%. Measured values of 90Sr agreed to within 1.7% of reference values for 10 minute count times, although longer count times can be used to improve detection limits and uncertainty. A single operator can complete the separation method for batches of 12-24 samples in as little as 3-4 hours.