基于PGNAA-XRF联合方法的铅汞混合样品检测的研究  

Study on Simultaneous Mercury and Lead Detection in Water Samples with PGNAA-XRF

作　　者：张焱[1,2] 单卿[1,2] 贾文宝[1,2] 吴旻剑 黑大千[1,2] 凌永生[1,2] 张新磊[1,2] 陈达[1,2] 

机构地区：[1]南京航空航天大学材料科学与技术学院,江苏南京210016 [2]江苏省高校放射医学协同创新中心,江苏苏州215000

出　　处：《光谱学与光谱分析》2016年第7期2271-2274,共4页Spectroscopy and Spectral Analysis

基　　金：国家自然科学基金项目(11405087和11375087);国家级大学生创新训练计划项目(201410287043);江苏高校优势学科建设工程课题资助

摘　　要：瞬发伽玛中子活化分析(PGNAA)技术用于溶液中重金属元素原位检测时,由于样品成分复杂,中子俘获截面较大的中子毒物(汞)元素,对截面较小的元素(铅)检测精度干扰很大,因此分析精度相对不高。为实现混合样品中多种重金属的高精度原位检测,提出了一种提高热中子俘获截面较低元素检出限的PGNAA-XRF联合检测方法,设计了一套联合检测混合样品中重金属元素的装置;使用MCNP软件,根据重金属元素的特征γ射线和特征X荧光的计数对样品的尺寸进行优化,得到较合适的样品尺寸高度和半径分别为33和16 cm;并模拟研究了Hg和Pb混合样品中的不同浓度(c_i)对瞬发特征γ射线强度(I_γ)和特征X荧光强度(I_X)的影响,模拟结果表明该混合样品中,Hg和Pb元素的I_γ和I_X均与c_i成良好的线性关系,通过探测Pb的X荧光信息,克服混合样品中高低热中子俘获截面元素间的竞争问题,能显著的改善Pb的检出限,最后拟合给出了PGNAA-XRF联合检测方法的经验公式,计算得到该装置对Hg和Pb元素的检出限分别为3.89和4.80 mg·kg^(-1)。Prompt gamma neutron activation analysis （PGNAA ） technology is used in heavy metals measurement .It is found that the detection accuracy of lead （Pb） is impacted heavily by mercury （Hg ） ,because of thermal neutron cross section of mercury is much bigger than lead .In this paper ,a new combined detection method was proposed to improve the lead measure-ment accuracy in situ environmental water rejects analysis by PGNAA-XRF .Thus ,a combined measurement facility was devel-oped to analyze the mercury and lead in water simultaneously .The geometry of set-up is determined by a series of simulations with the MCNP code to improve the detection efficiency of the prompt gamma-ray intensity （Iγ） and characteristic X-ray fluores-cence intensity （IX ） of element .The ideal sample height and cavity are 33 and 16 cm ,respectively .The influence of the relation-ship between Iγ ,IX and different concentration （ci ） of Hg and Pb was researched by MCNP calculations ,respectively .The sim-ulation results showed that there were good linear relationships between Iγ , IX and ci ,respectively .The empirical formula of combined detection method was proposed based on the above calculations .The limits of detection for Hg and Pb with the com-bined measurement instrument were 3.89 and 4.80 mg · kg^ -1 ,respectively .It is a significant increase in performance of the mercury and lead detection simultaneously .

关 键 词：瞬发伽玛中子活化分析 X荧光 重金属 蒙特卡罗 

分 类 号：O657.3[理学—分析化学]