三步离子交换法用于高精度测定硝酸盐卤水样品中硼同位素  

Three-step Ion Exchange Method for High Precision Determination of Boron Isotope in Nitrate Brine Samples

作　　者：马学海 马云麒[1,2] 宋建国 程怀德 杨剑[1,2,3] 海擎宇 李兴意[1,2,3] 李俊 MA Xue-Hai;MA Yun-Qi;SONG Jian-Guo;CHENG Huai-De;YANG Jian;HAI Qing-Yu;LI Xing-Yi;LI Jun(Key Laboratory of Comprehensive and Highly Efficient Utilization of Salt Lake Resources,Qinghai Institute of Salt Lake,Chinese Academy of Sciences,Xining 810008,China;Key Laboratory of Salt Lake Geology and Environment of Qinghai Province,Xining 810008,China;University of Chinese Academy of Sciences,Beijing 100049,China)

机构地区：[1]中国科学院青海盐湖研究所,中国科学院盐湖资源综合高效利用重点实验室,西宁810008 [2]青海省盐湖地质与环境重点实验室,西宁810008 [3]中国科学院大学,北京100049

出　　处：《分析化学》2020年第6期780-785,共6页Chinese Journal of Analytical Chemistry

基　　金：西北研究院‘一三五’重点培育项目和科技部专项项目(No.2012FY112600);中国科学院仪器设备功能开发技术创新项目(No.2020g102)资助.

摘　　要：用热电离质谱法(TIMS)测定样品的硼同位素时,共存的硝酸根(NO-3)会产生Cs2BO+2的同质异位素Cs2CNO+,使得被测样品11B/10B的比值降低。针对硝酸盐型盐湖自然卤水样品(NO-3的含量为1384 mg/L),利用三次离子交换法,即在传统的两步离子交换法(第一步过硼特效树脂进行硼的分离和纯化,第二步阴阳离子交换法去除硼以外的其它杂质阴阳离子)的中间,再增加一步阴离子树脂处理,以减少样品溶液中NO-3的含量,从而消除硼同位素测定过程中NO-3的影响。结果表明,三步离子交换法比常规的两步离子交换法能进一步减少NO-3含量的影响,从而有效降低同质异位素对硼同位素测定的干扰,样品中硼的回收率大于90%。此过程未发生硼同位素的分馏,可满足含硝酸盐卤水高精度硼同位素测定的需求,且有效缩短了测样时间。The nitrate(NO-3) will produce a Cs2CNO+isobaric of Cs2BO+2 when determining boron isotope of samples containing nitrate by thermal ionization mass spectrometry(TIMS), which reduces the ratio of 11B/10B in these samples and seriously interferes with the determination of boron isotope. However, the traditional two-step ion exchange method(ie. the first step of boron special effect resin, the second step of anion-cation exchange method) cannot effectively remove NO-3. In this study, the pretreatment process of boron isotope in samples from the natural nitrate-type brine(NO-3 content was 1384 mg/L) was carried out. Three-step ion exchange method(ie. adding a step anion resin based two-step method) was used to reduce the content of NO-3 in the sample solution and eliminate the influence of NO-3 ion in the determination of boron isotope. The results showed that the three-step ion exchange method could further eliminate the content of NO-3 compared with the conventional two-step ion exchange method, reducing the interference of the isobaric determination of boron isotope. The recovery of boron in the sample pretreated by the three-step ion exchange method was over 90%, which fully met the requirements of boron isotope determination. In this process, there was no fractionation of boron isotope. This method was suitable for the high-precision boron isotope determination of nitrate-containing brine and effectively shortened the detection time.

关 键 词：硝酸根离子 硼同位素 同质异位素 正热电离质谱 

分 类 号：O657.63[理学—分析化学] TS392[理学—化学]