Summary of Method

Strontium is separated and concentrated from 5-10 gram vegetation samples. Samples are muffled in zirconium crucibles 2-4 hours to destroy organic content. The residue is wet ashed with HNO3-H2O2 and then fused with 15g NaOH at 600°C for ten minutes. The fusion cakes are dissolved in water, transferred to 250mL centrifuge tubes and precipitated with calcium phosphate to facilitate matrix removal. Strontium is separated from matrix impurities and potentially interfering radionuclides in the sample using stacked 2mL and 1mL cartridges 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. Average chemical recovery of strontium is 64 + 4% for 5g samples and 70 + 8% for 10g samples. Measured values of 90Sr agreed to within 12% of reference values for 90 minute count times. The average time to complete the sample preparation is <8 hours.