Resolving isobaric interference towards the determination of 137Cs and 90Sr using laser-ionization mass spectrometry

Abstract

In any nuclear industry which follows a closed nuclear fuel cycle, determination of ⁹⁰Sr and ¹³⁷Cs present in high level liquid waste (HLLW) is of major concern because of its environmental risk, long half-life, high energy radiation and higher fission yield. The well-established techniques for determination of ⁹⁰Sr and ¹³⁷Cs in HLLW require separation of these elements in pure fractions for radiometric measurement or removal of isobaric interfering elements in the case of mass spectrometric methods. The present study demonstrates the potential use of the laser ionization mass spectrometry (LIMS) technique for quantitative estimation of ⁹⁰Sr and ¹³⁷Cs without prior chemical separation. LIMS with optimised laser parameters eliminates the isobaric interference in situ and shortcomings of conventional techniques. The present study is the first of its kind, to our knowledge, to resolve isobaric interfering elements using LIMS. The results on the optimum laser parameters, calibration plot and limit of detection for quantification of ⁹⁰Sr and ¹³⁷Cs using LIMS are discussed in this study. Results obtained from LIMS are compared with those of similar analysis using ICP-OES and it is found that LIMS provides a wider dynamic range for Cs and Sr compared to ICP-OES.