萃取色层法测定90Sr时消除210Bi干扰的修正方法

A modified method to eliminate ^(210)Bi interference in the analysis of ^(90)Sr by extractive chromatography

^(210)Bi是环境样品分析^(90)Sr过程中最重要的干扰核素之一。在二(2-乙基己基)磷酸酯(Bis(2-ethylhexyl)phosphate,HDEHP)萃取色层法分析^(90)Sr过程中,通过对淋洗液分段收集、测量并绘制淋洗曲线,发现铋、钇完全被吸附在色层柱上且二者无法完全分离,导致^(90)Sr测量结果偏高。对于部分环境样品(如土壤、气溶胶等),^(210)Pb-^(210)Bi的含量远高于^(90)Sr-^(90)Y,必须采取进一步的除铋措施。过柱分离后残留的^(210)Bi可以通过Bi_(2)S_(3)沉淀的方法去除;未进行Bi_(2)S_(3)沉淀除铋或除铋不完全时^(210)Bi仍有残留。因此推荐一种利用衰变规律通过对样品源重复测量、运用公式修正的方法消除^(210)Bi干扰。试验结果表明:^(210)Bi与^(90)Sr活度比≤5时,经修正后的^(90)Sr结果与参考值的相对偏差在23%以内。环境样品通过修正方法计算的^(90)Sr结果与Bi_(2)S_(3)沉淀除铋后的测量结果基本一致。

[Background]^(210)Bi is one of the most important interferences in the analysis of ^(90)Sr by extractive chromatography.It is verified by the leaching curve that bismuth and yttrium are completely adsorbed on the chromatographic column in the bis(2-ethylhexyl)phosphate(HDEHP)extraction chromatography,and this two components can not be completely separated,resulting in higher measurement results of ^(90)Sr.[Purpose]This study aims to provide a modified method to eliminate ^(210)Bi interference in the analysis of ^(90)Sr by bis(2-ethylhexyl)phosphate(HDEHP)extraction chromatography.[Methods]By collecting the eluent,measuring the content of strontium,yttrium,lead and bismuth in the eluent and drawing the leaching curve,the adsorption and elution behavior of strontium,yttrium,lead and bismuth in the P204 resin were investigated.The residual ^(210)Bi after column separation was experimentally removed by Bi_(2)S_(3) precipitation or by measuring the sample source repeatedly and correcting the result with formulas.[Results]The experimental results show that the relative deviation between the modified ^(90)Sr activity and the reference value is within 23%when the activity ratio of ^(210)Bi to ^(90)Sr is not bigger than 5.The results of ^(90)Sr calculated by the modified method for environmental samples are in good agreement with the measured results after bismuth removal by Bi_(2)S_(3) precipitation.[Conclusions]The interference of ^(210)Bi in the analysis of ^(90)Sr by extractive chromatography can be eliminated by measuring the sample source repeatedly and correcting the result with formulas.