Determination of strontium 90 in environmental samples by triple quadrupole ICP-MS and its application to Fukushima soil samples

Abstract

The determination of ⁹⁰Sr by ICP-MS is capable of providing a high sample throughput compared with radiometric analytical methods. Although the isobaric interference caused by ⁹⁰Zr ions can be reduced by reaction with oxygen, the high background caused by stable ⁸⁸Sr has made it difficult to determine ⁹⁰Sr by conventional ICP-MS. In this study, a rapid and sensitive method was developed for the determination of ⁹⁰Sr using triple quadrupole ICP-MS. The MS/MS configuration improves the abundance sensitivity by more than two orders of magnitude (5 × 10⁻¹²), and the detection limit for ⁹⁰Sr in 1 g environmental samples was 0.6 Bq kg⁻¹. The applicability of the method to the measurement of ⁹⁰Sr in environmental samples was demonstrated by analysis of certified reference materials (soil: IAEA 375; plant: IAEA 330, IAEA 373) contaminated by the Chernobyl accident. The measured ⁹⁰Sr radioactivities in the samples were consistent with values determined by radiometric analysis, within analytical error. The measured ⁹⁰Sr concentration in IAEA 372 was 610 ± 40 Bq kg⁻¹ (SD, n = 3) (Decay correction was made to December 1, 2016). This method provides a powerful tool for the investigation of radiostrontium contaminations in the Fukushima area and elsewhere.