尿中铀及同位素测定和内照射评价

发布时间：2018-01-28 10:02

本文关键词： 尿铀同位素丰度 TBP萃取色层电感耦合等离子体质谱(ICP-MS) 剂量估算　出处：《中国疾病预防控制中心》2012年硕士论文　论文类型：学位论文

【摘要】：铀是广泛存在于自然环境中的长寿命放射性元素,通过饮水和食物链等途径进入人体。正常人体中的铀主要来自于摄入的水、食物和空气；涉铀职业人员体内的铀则主要来源于核燃料循环、核设施运行以及铀同位素应用等过程中的被动摄入。铀被人体摄入后,主要蓄积于肝脏、肾脏和骨骼中,对人体的损伤表现在放射性损伤和化学损伤,根据剂量大小,可引起急性或慢性中毒,诱发多种疾病。铀有三种天然同位素238U、235U和234U,丰度分别为99.27%、0.72%和0.0055%。在放射性核素毒性分组中,234U属于极毒组,235U、238U属于低毒组。由于234U的比活度相当大,虽然其含量低,但是对剂量的贡献却不可忽略。近些年,随着贫铀(235U/238U丰度比约为0.25%)在世界范围内受到越来越多的关注,为了满足放射性危害评价和突发事件应急的需要,准确测量人体尿中总铀含量及其同位素丰度比,估算其剂量贡献是职业危害评价和健康危害评价的重要指标之一,也是保证公众安全应急分析的措施,因此,开展尿中铀及同位素分析方法的研究具有重要的意义。本工作研究了TBP萃淋树脂分离尿中铀、电感耦合等离子体质谱(ICP-MS)测定铀及其同位素丰度比的方法,优化实验条件并建立了分析流程。主要研究包括以下内容： (1)建立了TBP萃淋树脂快速分离尿样中铀的流程通过铀的标准溶液条件实验,研究了上柱酸度及淋洗酸度、洗脱剂和柱流速对TBP萃淋树脂分离铀的影响,确定样品的上柱酸度和淋洗酸度、柱流速和洗脱剂;配制模拟尿样,研究TBP萃淋树脂对干扰元素的分离、铀的回收率和不同体积样品对分离效果的影响。 (2) ICP-MS分析铀同位素丰度比的研究研究了同质异位素和多原子离子干扰、仪器参数、质量偏倚以及死时间对ICP-MS分析铀同位素丰度比精度的影响,确定了最佳仪器参数和质量控制方法,并对质量偏倚和死时间进行校正。 (3)建立并应用ICP-MS快速分析方法分析实际尿样中铀和同位素丰度比通过开展TBP萃淋树脂对实际尿样分离的研究,建立了ICP-MS快速分析人体尿中铀及同位素的方法流程,并对实际尿液样品进行了分析,并根据实验结果以及考虑便于实验操作,提出ICP-MS分析尿样中铀及同位素丰度比的最佳流程为：100mL样品预处理,柱流速和上柱酸度分别选择1.2mL/min、5mol/L HNO3,40mL5mol/L HNO3淋洗色层柱,去离子水作为洗脱剂,ICP-MS测定。在此条件下,尿样中铀的回收率达90%以上,净化系数均大于103。 (4)对ICP-MS分析实际尿样中铀及同位素丰度比的结果进行不确定度的评定。 (5)根据ICRP的剂量系数方法,利用尿中铀浓度结合经验公式计算摄入量,开展内照射剂量的估算,估算结果小于或略高于铀、钍系照射的年有效剂量世界平均值。
[Abstract]:Uranium is a long life radioactive element widely existing in the natural environment, which enters the human body through drinking water and food chain. The uranium in normal human body is mainly from the water, food and air. Uranium in the human body is mainly derived from the passive intake of uranium in the nuclear fuel cycle, the operation of nuclear facilities and the application of uranium isotopes. Uranium is mainly accumulated in the liver, kidneys and bones after being ingested by the human body. The damage to human body is manifested in radiation damage and chemical injury. According to the dose size, it can cause acute or chronic poisoning and induce many diseases. Uranium has three natural isotopes, 238U 235U and 234U, the abundance of which is 99.270.72% and 0.00555.In the radionuclide toxicity group. 234U belongs to the extremely virulent group and 235U / 238U belongs to the low toxicity group. The specific activity of 234U is quite large, although its content is low, but the contribution to the dose can not be ignored in recent years. With the depleted uranium 235U / 238U abundance ratio of about 0.25) in the world more and more attention, in order to meet the needs of radiological hazard assessment and emergency response. Accurate measurement of total uranium content and isotopic abundance ratio in human urine and estimation of its dose contribution are one of the important indicators for occupational hazard assessment and health hazard assessment, and are also measures to ensure public safety emergency analysis. It is of great significance to study the analytical methods of uranium and isotopes in urine. A method for the determination of uranium and its isotopic abundance ratio in urine by TBP extraction resin and ICP-MS has been studied. The experimental conditions are optimized and the analysis flow is established. The main research includes the following: The rapid separation of uranium from urine by TBP extraction resin has been established. The effects of upper column acidity, elution acidity, eluant and column flow rate on the separation of uranium by TBP extraction resin were studied by experiments on the standard solution conditions of uranium. The upper column acidity and elution acidity of the sample were determined. Column flow rate and eluent; The effects of TBP extraction resin on the separation of interfering elements, the recovery of uranium and the effect of different volume samples on the separation were studied. Analysis of uranium isotopic abundance ratio by ICP-MS The effects of heterotopic and polyatomic ion interference, instrumental parameters, mass bias and dead time on the accuracy of ICP-MS analysis of uranium isotopic abundance ratio were studied. The optimal instrument parameters and quality control methods were determined, and the mass bias and dead time were corrected. Establishment and application of ICP-MS rapid analytical method for analysis of uranium and isotopic abundance ratios in real urine samples By studying the separation of real urine samples by TBP extraction resin, the method flow of rapid analysis of uranium and isotopes in human urine by ICP-MS was established, and the actual urine samples were analyzed. Based on the experimental results and convenient operation, the optimal procedure for the determination of uranium and isotopic abundance ratio in urine by ICP-MS was proposed as follows: 1: 100ml sample pretreatment. The column flow rate and the acidity of the column were 1.2 mL / min ~ 5 mol / L HNO _ 3 and 40 mL / L ~ 5 mol / L HNO3 elution column respectively, and deionized water was used as eluent. Under these conditions, the recovery rate of uranium in urine is over 90%, and the purification coefficient is higher than 103. The uncertainty of the results of ICP-MS analysis of the abundance ratio of uranium and isotopes in real urine samples is evaluated. (5) according to the dose coefficient method of ICRP, the intakes were calculated by uranium concentration in urine combined with empirical formula, and the internal radiation dose was estimated. The estimated results were less than or slightly higher than that of uranium. The world average annual effective dose of thorium irradiation.
【学位授予单位】：中国疾病预防控制中心
【学位级别】：硕士
【学位授予年份】：2012
【分类号】：R142

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