Determination of strontium-90 in water and urine samples using ion chromatography

Abstract

A semi-automated method was developed for the determination of ⁹⁰Sr in water and urine samples using ion chromatography. Yttrium-90 in secular equilibrium with ⁹⁰Sr was initially extracted from the sample solution buffered to pH 5 using a high-capacity iminodiacetate chelating resin. At this pH, transition metals, lanthanides and actinides were extracted by the resin. The extracted metals were then transferred on to a separator column where they were separated and eluted as weak acid anionic complexes. The transition metals were eluted first by using a pyridine-2,6-dicarboxylate eluent, then the lanthanides, actinides and ⁹⁰Y were eluted from the column by using an oxalate–diglycolate eluent. The fraction containing ⁹⁰Y was then collected and β-counted. For water samples, a minimum of sample preparation was required prior to chromatography, whereas an oxalate coprecipitation was included as a preconcentration step for urine samples. The derived recoveries for ⁹⁰Sr for surface water, rain water and urine samples were 91.7 ± 1.8, 91.9 ± 1.6 and 90.0 ± 2.7%, respectively, and the minimum detectable activity using gas flow proportional counting was 8 mBq.