加速器质谱^(14)C微量样品制备研究  

Investigation of Sub-milligram Sample Preparation for ^(14)C Determination by Accelerator Mass Spectrometry

作　　者：刘圣华[1,2] 吕哲 杨劲松 杨庆华[1] 张慧[3] 于波 张曼丽 LIU Shenghua;LYU Zhe;YANG Jinsong;YANG Qinghua;ZHANG Hui;YU Bo;ZHANG Manli(Key Laboratory of Quaternary Chronology and Hydro-Environmental Evolution of China Geological Survey,Institute of Hydrology and Environmental Geology,Chinese Academy of Geological Sciences,Shijiazhuang 050061,China;School of Earth Sciences and Resources,China University of Geosciences(Beijing),Beijing 100083,China;Key Laboratory of Groundwater Science and Engineering of Ministry of Natural Resources,Institute of Hydrology and Environmental Geology,Chinese Academy of Geological Sciences,Shijiazhuang 050061,China)

机构地区：[1]中国地质调查局第四纪年代学与水文环境演变重点实验室,中国地质科学院水文地质环境地质研究所,河北石家庄050061 [2]中国地质大学(北京)地球科学与资源学院,北京100083 [3]自然资源部地下水科学与工程重点实验室,中国地质科学院水文地质环境地质研究所,河北石家庄050061

出　　处：《原子能科学技术》2021年第6期968-975,共8页Atomic Energy Science and Technology

基　　金：河北省自然科学基金资助项目(D2020504018,D2020504008);国家自然科学基金资助项目(41703020,41807428)。

摘　　要：虽然Zn/Fe火焰封管法能获得常规量样品(约1 mgC)的低本底高精密度的(14C)数据,但微量样品(<1 mgC)的制备主要基于H2/Fe在线催化还原法,Zn/Fe火焰封管法却鲜有研究报道。本文基于Zn/Fe火焰封管法对现代碳标准样品OXⅡ和本底样品IHEG-Coal进行微量样品0.04~1.0 mgC制备,探讨该方法中样品量对石墨束流性能的影响,估算全实验流程中所引入的现代碳和死碳污染量,并对石墨制备真空系统的微量样品制备能力进行评估。结果表明:加速器质谱测试过程中的束流强度表现与样品质量存在明显正相关关系。全实验流程中引入的外源性现代碳污染量为1.0~3.0μgC,外源性死碳污染量为0.5~3.0μgC。14C测试精密度与准确度严重依赖于样品量,当样品量>0.5 mgC时,现代碳标准样品OXⅡ的现代碳比值Fm为1.342 7±0.003 9,本底样品IHEG-Coal的测试年龄为(46 192±301) a,显示其测试的精密度与准确度较可靠。Although routine sample mass(about 1 mgC)prepared by flam sealed tube Zn/Fe method can obtain the measurement data with high precision,accuracy and low background,most of sub-milligram(<1 mgC)sample preparation are based on online H 2/Fe method rather than flam sealed tube Zn/Fe method.In the present study,sub-milligram(between 0.04-1.0 mgC)samples with the modern radiocarbon standard of OX Ⅱand the background sample of IHEG-Coal were prepared based on flam sealed tube Zn/Fe method.The effect of sample mass on beam current was discussed.The magnitude of exogenous modern-carbon and exogenous dead-carbon contamination on sub-milligram mass sample was calculated,subsequently evaluated the capability of the small sample preparation vacuum line.The results show that there is a significant positive correlation between the beam current and the sample mass.The exogenous modern-carbon contamination is estimated to be 1.0-3.0μgC during the whole preparation procedure,and that is 0.5-3.0μgC for dead-carbon.The precision and accuracy of ^(14)C results are strongly depended on the sample size.When the sample mass is more than 0.5 mgC,the F m value of standard sample OX Ⅱis 1.3427±0.0039 and the age of background sample IHEG-Coal is(46192±301)a,which shows that the precision and accuracy are reliable for this system.

关 键 词：^(14)C 制备 微量样品 外源碳污染 Zn/Fe火焰封管法 

分 类 号：O657.63[理学—分析化学] O613.71[理学—化学]