Comparison of different methodologies for the ⁹⁰Sr determination in environmental samples

Area of Science:

• Environmental Science
• Radiochemistry
• Analytical Chemistry

Background:

• Accurate determination of strontium-90 (⁹⁰Sr) is crucial for environmental monitoring and risk assessment.
• Various isolation and detection methods exist, but their efficiency can be matrix-dependent.
• Proficiency testing (PT) is essential for validating analytical methods.

Purpose of the Study:

• To compare different strontium isolation and detection procedures for ⁹⁰Sr determination in environmental samples.
• To evaluate the impact of sample matrix constituents on strontium isolation efficiency (chemical yield).
• To assess the reliability and accuracy of ⁹⁰Sr determination across different sample types.

Main Methods:

• Four strontium isolation methods were tested: Sr resin, AnaLig^®Sr01, anion exchange resins, and a combination of anion exchange and Sr resin.
• Two detection methods were employed: Cherenkov counting of ⁹⁰Y and proportional counting of ⁹⁰Sr(⁹⁰Y).
• Methods were validated using proficiency test samples (water, soil, vegetation) and animal bone samples.

Main Results:

• Strontium isolation efficiency varied significantly with sample type and separation methodology.
• Sr resin showed decreased yield in the presence of high Ca, Sr, and Na concentrations, particularly for vegetation samples (21% average yield).
• Combined anion exchange and Sr resin yielded the highest average recovery (78%) for soil samples.
• Accuracy of ⁹⁰Sr determination was linked to the accuracy of yield determination, not solely high chemical yield.
• 96% of PT results fell within acceptable z-values (0 to ±2), with 90% deviating less than 20% from assigned values.

Conclusions:

• The choice of strontium isolation method must consider the sample matrix to ensure reliable ⁹⁰Sr determination.
• Accurate yield determination is paramount for achieving accurate ⁹⁰Sr results, irrespective of the chemical yield achieved.
• The evaluated methods provide accurate ⁹⁰Sr determination in environmental and bone samples, as confirmed by PT results.