Activation Analysis of Gadolinium Impurity in High Purity Europium Oxide

Abstract

An analytical method for determining Gd impurity in high purity Eu₂O₃ is proposed, which makes use of neutron activation and cation-exchange separation to examine its suitability as target material for the production of ^{152 m, 152, 154}Eu.

Long-term irradiation of an Eu sample resulted in ¹⁵³Gd activity amounting to 1.8 times that of the same nuclide produced from an equal quantity of Gd by (n, γ) reaction. This experimental value is quite consistent with that obtained by calculation under the assumption that the ¹⁶³Gd results from nuclear reaction on ¹⁵¹Eu induced by secondary neutrons.

For the accurate determination of Gd, Gd impurity was separated from the Eu sample prior to neutron irradiation in order to reduce the self-shielding effect in the Eu sample. Separation by cation-exchange with α-hydroxyisobutyrate (0.33 M, pH 3.77) made it possible to reduce the content of Eu in the Gd fraction below 7×10^?3%. This sufficed to assure that the ¹⁵⁹Gd content in ^152mEu was smaller than 1×10^?3%. For the determination of Gd content below 10⁴ ppm, however, should necessitate further purification of the irradiated Gd fraction.     

地质样品中痕量铑的火试金预富集中子活化分析

简述了铅试金和镍锍试金富集地质样品中痕量铑的分离方法,并结合中子活化分析测量了5种地质标准物质中铑的含量。铅试金法的流程回收率（n=4）为81.5%±1.2%;镍锍试金法的流程回收率（n=6）为75.1%±3.9%,对简单化学标准和地质标准物质基体,铑的回收率相近。对5种地质标准物质中铑含量的分析结果与标准值在不确定度范围内一致。铅试金中子活化法可实现10^－9铑含量的准确测量,镍锍试金中子活化法可实现10^－10铑含量的准确测量。对两种富集方法中的干扰因素进行了讨论,并对铅的自吸收效应进行了修正。探测极限的计算结果表明：镍锍试金预富集并用平面锗探测器测量,可获得更好的分析灵敏度。     

污水中可吸附有机卤素（AOX）的中子活化分析

可吸附有机卤素（AOX）是一项表征有机卤化物的国际性水质指标。建立了中子活化分析水体AOX的方法,对氯、溴、碘的检出限分别为60 ng、15 ng和6 ng。采用中子活化技术测定了某纸浆厂污水和医院污水可吸附有机卤素的含量,结果表明,纸浆厂和医院污水中的有机卤素污染问题不容忽视。     

发射光谱法测定二氧化碲中的杂质元素

采用发射光谱粉末法同时测定二氧化碲Pb、Mn、Ba、Sn、Fe、Co、Ti、Cd、Cr、Al、Ca、Si、B、Bi、V、Ni、Sb、Zn、Ag、Mg、Cu18个金属元素，选择石墨作载体，直接压样于石墨电极中，简单，快速而准确。其回收率在80%-120%范围内，相对标准偏差小于8%，用于样品的测定取得了满意的结果。     

利用~(252)Cf源中子活化分析人体血液中Na元素浓度

介绍了利用~(252)Cf源中子活化分析人体血液样品中Na元素浓度的分析方法。该方法将人体血液样品放入自制的照射桶中,Na元素经~(252)Cf源中子活化后产生放射性的~(24)Na,用γ谱议测量~(24)Na的比活度,求得人体血液样品中Na元素浓度。对6个样品的Na元素浓度进行测量,其均值较报道的均值1.81 mg/mL的偏差仅为2.9%。该方法的探测下限为0.216mg/mL,测量结果的不确定度为0.3210.403 mg/mL。     

微堆超热中子活化分析在地学样品测定中的应用

微型中子源反应堆(简称微堆)是以高浓铀(235 U)作燃料的轻水欠慢化型反应堆,辐照孔道内存在有较大份额的超热中子和快中子,适合进行超热中子活化分析(ENAA)的实验研究。地质样品成分复杂,在用普通的中子活化分析时,基体元素影响了部分元素的准确测定。为降低基体成分的本底干扰、改善目标元素的测量精密度和检出限,可采用超热中子活化分析的方法。本文利用微堆上安装的屏蔽材料为镉的超热中子辐照孔道,测定了元素周期表中67种元素的约130个核素的镉比,讨论了在超热中子活化分析中某些元素的有利因子及铀裂变和(n,p)反应的干扰情况,验证了微堆ENAA方法在地质科学样品检测中的实际应用,证实利用本方法可测定地学样品中20余种元素,其检出限、精密度和准确度均得到了较明显的改善。该法是常规活化分析方法必要的、有益的补充。     

中子活化分析在当代无机痕量分析计量学中的作用Ⅰ.相对法中子活化分析(NAA)作为比较基准法资格的论证

丛三个方面讨论了NAA在现代无机痕量分析计量学中的地位和作用：(1)相对法NAA作为比较基准法资格的论证;(2)参量法NAA作为相对法NAA“辅助”方法的特殊功能;(3)NAA在适用于微分析质量控制的新一代标准物质表征中的作用。作为首篇,本文对NAA,特别是纯仪器NAA(INAA)的原理、不确定度和溯源性作一分析,说明相对法NAA在当前最高水平上满足了“物质量咨询委员会”(Consultative Committee for Amount of Substance,CCQM)关于比较基准法的判据。举例分析了NAA的溯源性和不确定度,进一步证明NAA的比较基准法资格,并讨论了NAA作为比较基准法的优点、当前的适用范围和可能的未来进展。最后列出了几个有关的计量学术语的定义和国际规范。     

中子活化法研究硒在人体组织中的亚细胞分布

用细胞器的差速离心分离技术和中子活化分析法研究了微量元素硒在人体重要组织中的亚细胞分布 ,并用国际标准参考物质小牛肝 (NIST 15 77a)、马肾 (IAEA H8)等检验分析结果的准确性。结果表明 :不同个体的硒水平差异较大 ;在所研究的组织中 ,肾脏中硒含量最高。不同组织中硒的亚细胞分布模式明显不同 ,硒的浓度从高到低依次为 :肝脏 ,线粒体 >细胞核 >胞液 >溶酶体、微粒体 ;肾脏 ,细胞核 >线粒体 >胞液 >溶酶体、微粒体 ;心脏 ,细胞核、线粒体 >胞液、溶酶体、微粒体     

白令海和北冰洋海水中铱的阴离子交换预富集-中子活化分析

研究了用阴离子交换预富集 中子活化法测定海水中铱的分析方法。192Ir示踪实验结果表明,在0 05～1 2mol/LHCl介质中,酸度越低越有利于树脂对Ir的吸附;阴离子交换法对pH=1 5的酸化海水中痕量Ir的回收率为89%;聚乙烯瓶和pH=1 5的酸化条件可以长期保存海水中的Ir。在超净实验条件下,用阴离子交换预富集 中子活化法测定了白令海和北冰洋垂直剖面样品中Ir的浓度,结果分别为(0 85～3 58)×10-12g/L(白令海,采集深度为0～3504m)和(1 26～1 97)×10-12g/L(北冰洋,采集深度为25～1900m),试剂空白值为(0 18～0 20)×10-12g/L。     

Enhancement of the Mutual Separation of Lanthanide Elements in the Solvent Extraction Based on the CMPO-TBP Mixed Solvent by Using a DTPA-Nitrate Solution

The mutual separation behavior of rare earth elements was studied in the system based on the neutral extractant CMPO (n-octyl(phenyl)-N,N-diisobutylcarbamoyl methylphosphine oxide) and aminopolyacetic acid DTPA (diethylenetriamine pentaacetic acid). The extractability of lanthanides decreased monotonously with increasing of atomic number in the system of 0.2 M CMPO-1.0 M TBP-n-dodecane (TRUEX solvent) and 0.05 M DTPA-NaNCO₃ or hydroxylamine nitrate (HAN) solution. The separation factor of La/Lu was 6,600 using 0.05 M DTPA-3M NaNO₃ solution (initial pH=2.0). The mutual separation of lanthanides in the CMPO/DTPA system was greatly improved when compared with the general TRUEX system. The separation factor was not affected by the initial pH of the solution (1.8–2.2), the salting out reagent (NaNO₃ and HAN), or its concentration (2, 3 M). The experimentally obtained separation factors of lanthanide elements were reproduced by a simple model based on the distribution ratios in the TRUEX extraction system and the stability constants of DTPA-metal complex. The mutual separation between light lanthanides is attributed to the selectivity of DTPA, while CMPO mainly influences the separation of heavy lanthanides.     

Fundamental Study on Separation of Uranium from Other Metals by Solvent Extraction with Tributylphosphate or Tributylphosphine Oxide in Molten Naphthalene

The extraction behaviors of U and other metals has been studied as functions of the concentration of nitric acid or hydrochloric acid in aqueous media and as functions of the amount of naphthalene as diluents, when tributylphosphine oxide (TBPO) or tributylphosphate (TBP) was used as a extractant. Uranium could be quickly extracted over 95% from 25 cm³ of the 1 mol·dm^?3 nitric acid solution with 150 mg of TBPO and 350 mg of naphthalene at 80°C. On the other hand, about 80% of U could be extracted under better conditions, when 25 cm³ of 4 mol·dm^?3 nitric acid solution and 1cm³ of TBP and 3 g of naphthalene were used. In either case, the extraction phases could be easily separated as a solid by cooling to room temparature. Uranium could be separated from alkaline earth metals, transition metals and rare earth metals, and U was efficiently concentrated by extraction with molten naphthalene, compared with usual solvent extraction which used toluene, etc.