放射性核素^(14)C在生物学中的应用

从分子生物学、古生物学及生物医学3个方面论述了放射性核素14C的应用,并指出了其应用的缺陷及今后在应用研究中应注意的问题。

Direct analysis method of^(14)C radioactivity concentration in urine samples

Objective:To establish a rapid analysis method for the activity concentration of carbon-14(14C)in urine,in order to estimate the internal dose of 14C exposure,and to protect the health of occupational population.Methods:Liquid scintillation counting(LSC)combined with the function of transformed spectral index of the external standard spectrum(tSIE)was used to measure the quenching level and counting rate,and the spiked urine samples with different shades of color were measured by LSC.After establishing the efficiency-quenching curve,the quenching correction and activity concentration analysis of the actual samples were carried out.Results:By LSC and the data fitting,the relationship between efficiency and quenching index could be represented using the equation y=0.0013x-0.0177(R^(2)=0.978).Three actual spiked samples were tested to verify this method,with recoveries of 97%,102%,and 89%,respectively.14C activity concentration of 4 actual urine samples were 0.12,0.11,0.10 and 0.08 Bq/mL,respectively,while the corresponding extended relative uncertainties were 0.0652,0.0929,0.0893 and 0.1043,respectively.Conclusion:The direct analysis method of 14C activity concentration in urine samples was established using LSC.The recovery of 14C activity concentration in urine samples showed that the proposed method had relatively high accuracy.By studying on the source of uncertainty,the uncertainty of the analysis results mainly came from the statistical error of LSC,and the uncertainty component of counting efficiency.

~3H和^(14)C标记药物的制备及其质量控制

~3H和^(14)C标记药物广泛应用于新药研究和药物残留分析等领域,是用来阐明药物代谢、处置过程及评价药物残留危害的完美工具。~3H和^(14)C标记药物还可用于研究物质的生物化学特性,揭示生物合成途径和酶促反应机制,阐明有机反应机制和解决环境科学领域诸多问题。放射性示踪研究可提供化合物分子及其分解产物、代谢产物、相关物质的定量信息,在新药或待开发药物的药理学与毒理学研究中,拥有不可代替的作用,是利用大部分药物分子中含有H或C原子的特点,用适当标记制备方法,将药物分子中原有的H或C原子用~3H或^(14)C等放射性原子替代,用于后续放射性示踪研究的一种特殊手段。~3H和^(14)C标记药物的制备包括选择、评估和优化放射性标记合成路线和工艺;挑选合适的~3H和^(14)C前导物及中间体;常规合成规模改造成微量合成规模;优化反应条件和收率;最后还要进行放射性标记化合物的结构确证,分析测量其化学纯度、放化纯度、比活度和标记位置以及相关质量控制项目。由于~3H和^(14)C标记药物对药物研发领域的重大影响,本文采用举例讨论方法,对~3H和^(14)C标记药物的制备策略、技术路线选择、合成方法、微量合成改造及其质量控制技术进行了较为详细的论述。

核反应堆退役放射性石墨处理处置技术

针对反应堆退役过程中大量放射性石墨的处理处置需求,阐述了目前应用最主要的陆地处置、海洋处置和焚烧三种方法,其中作为固体废物处置需要将放射性石墨进行预处理,方法包括水泥固化、涂层包覆、高温自蔓延;海洋处理等技术;焚烧技术主要有固定床和流化床焚烧、激光焚烧和蒸汽热解等技术。本文认为焚烧可以大幅降低放射性石墨处置量,如能同时实现^(12)C和^(14)C同位素的分离,提取富集获得丰度较高的^(14)C同位素,实现^(14)C核素的资源化利用,将极大的提高退役处理过程的技术经济性。