电感耦合等离子体质谱测定铀样品年龄方法研究

铀样品年龄与生产时间密切相关,是核法证学调查核材料来源属性的一个重要参数。本文研究建立了利用²³⁰Th/²³⁴U原子数比测定铀样品年龄的分析方法。分别用²²⁹Th和²³³U稀释剂进行铀样品同位素稀释,利用TEVA树脂对样品中的铀和钍进行分离处理,用多接收电感耦合等离子体质谱测量²²⁹Th/²³⁰Th和²³³U/²³⁴U原子数比,根据铀年龄计算公式通过²³⁰Th/²³⁴U原子数比可得到样品的铀年龄。采用该方法对CRM U850和U010标准样品进行了年龄测定,结果与美国劳伦斯·利弗莫尔国家实验室的测量结果一致,但较实际年龄偏大,可能是由于生产时纯化过程不完全,导致有残留的²³⁰Th在样品中。本文所建立的方法可用于铀样品²³⁰Th-²³⁴U模型年龄的测定,为核法证学调查提供重要信息。     

Lead isotopes reveal different sources of lead in balsamic and other vinegars

Fifty-eight brands of balsamic vinegars were analyzed for lead concentrations and isotopic compositions (²⁰⁴Pb, ²⁰⁶Pb, ²⁰⁷Pb, and ²⁰⁸Pb) to test the findings of a previous study indicating relatively high levels of lead contamination in some of those vinegars — more than two thirds (70%) of them exceeded California's State Maximum Level (34 μg/L) based on consumption rates ≥ 0.5 μg Pb per day. The Lead isotopic fingerprints of all those vinegars with high lead concentrations were then found to be primarily anthropogenic. This isotopic analysis unquestionably reveals multiple contamination sources including atmospheric pollutant Pb and an unidentified contamination source, likely occurring after grape harvest. Organically grown grape vinegars display the same Pb content and isotopic signatures as other vinegars. This implies that pesticides might not be a significant source of pollutant Pb in vinegars. A significant post-harvest contamination would be inherited from chemicals added during production and/or material used during transport, processing or storage of these vinegars. This is consistent with the highest Pb levels being found in aged vinegars (112 ± 112 μg/L) in contrast to other vinegars (41.6 ± 28.9 μg/L) suggesting contamination during storage. It is, therefore, projected that lead levels in most vinegars, especially aged balsamic and wine vinegars, will decrease with improvements in their manufacture and storage processes consequential to recent concerns of elevated levels of lead in some vinegars.     

U-Pb定年锆石标准~(176)Hf/~(177)Hf比值的多接收器电感耦合等离子体质谱测定

利用MicromassIsoprobe型多接收器电感耦合等离子体质谱(MCICPMS)测定UPb定年国际锆石标准91500、Temora和本实验室锆石工作标准样We1的176Hf/177Hf比值。对添加Zr的室内Hf标准溶液HfGIG的模拟实验表明:Zr/Hf≤120时,Zr对Isoprobe型MCICPMS的Hf同位素比值测定值没有明显的影响,所以锆石Hf分离纯化流程采用改进的高温高压氢氟酸溶解和其后的一个离子交换分离流程实现,整个流程Hf的回收率高于90%。176Hf/177Hf比值测定采用JMC475Hf标准溶液(176Hf/177Hf=0.282160)进行外部校正并监控仪器漂移。标准样91500、Temora和We1平均的176Hf/177Hf比值测定结果分别为(0.282310±0.000034)、(0.282706±0.000020)和(0.281534±0.000009)。上述每个结果包括至少7组独立的锆石样品的溶解、分离和测定,表明标准样91500、Temora和We1是Hf同位素组成均一的。本实验结果对于激光熔蚀多接收器电感耦合等离子体质谱(LAMCICPMS)锆石原位176Hf/177Hf比值测定校正方法的检验具有重要意义。     

多接收电感耦合等离子体质谱法测量分离样品中Li同位素丰度比

Isotopic abundance ratios in chemical exchange separation sample were determined using GV IsoProbe multicollector-inductively coupled plasma mass spectrometry (MC-ICP-MS). GV IsoProbe MC-ICP-MS was calibrated by the lithium nature isotope reference material. Calibrated GV IsoProbe MC-ICP-MS was used to determine lithium isotope abundance ratio which was produced through chemical change separation.     

碰撞池-多接收电感耦合等离子体质谱分析硅同位素的方法研究

通过更换仪器进样系统、改变溶液基体、调节碰撞气的种类和流量以及调节质量分辨率等参数,建立了碰撞池-多接收电感耦合等离子体质谱（Collision Cell-MC-ICP-MS）测定硅同位素丰度组成的分析方法。实验结果表明:使用PFA雾化器、Pt锥和蓝宝石材质的矩管可有效降低仪器本底;调节狭缝宽度、中心杯位置等可提高仪器的质量分辨率,实现硅同位素离子与同量异位素干扰离子在一定程度上的分离;选择氖气（Ne）和氩气（Ar）的混合气作为碰撞气、降低溶液中四甲基氢氧化铵（TMAH）浓度等能有效降低多原子离子的干扰。在此基础上,分析了样品WASO 04和GBW(E)080272中硅同位素的丰度组成,同位素丰度比R_30/28的测量精度达到0.02%。将样品WASO 04作为参考标准时,样品GBW(E)080272中的硅同位素分馏系数δ³⁰Si为-1.57‰。     

多接收电感耦合等离子体质谱测定182Hf/180Hf的方法研究

¹⁸²Hf is an important radionuclide for nuclear research and supernova explosions. The reference material of ¹⁸²Hf/¹⁸⁰Hf is especially important, but not yet available. Considering the demands of nuclear science research an development, a method was developed to measure the ratio of ¹⁸²Hf/¹⁸⁰Hf with high-precision by using multi-collector inductively plasma mass spectrometry (MC-ICP-MS). The operating parameters of MC-ICP-MS were optimized. Isobar interference and mass bias were studied. The measurement result of the ratio of ¹⁸²Hf/¹⁸⁰Hf was obtained based on deducting the interference of isobaric ¹⁸²W.     

多接收电感耦合等离子体质谱法测量痕量钚同位素

The isotopic analysis of 232Pu plutonium in 5×10-12 g/g samples using a multi-collector inductively coupled plasma mass spectrometry (MC-ICPMS) is described. IRMM-290b and uranium (UTB750) were used to correct the metrical data, and the analytical precision is about 0.5%.     

MC-ICP-MS标样-样品交叉测试法测定石笋样品的230Th/U年龄

借鉴国际上已经建立的方法,本研究设计了一套便捷的UTEVA树脂分离纯化U与Th的化学流程,以及多接收电感耦合等离子体质谱测量U/Th同位素的方法,用于精确测定石笋样品的²³⁰Th/U年代。U/Th同位素的测量采用标样-样品交叉测试法（standard-sample bracketing）,即在测量未知样品之前和之后分别测量标准样品的同位素,通过外部归一化和线性内插法估算测量未知样品时仪器的校正因子,如质量歧视和二次电子倍增器相对于法拉第杯的增益。为检验该方法的可靠性,本研究分析了国际U标准样品Harwell uraninite-1（HU-1）、U/Th内用标准样品MFT和已知年代石笋样品的U/Th同位素。结果显示：HU-1的δ²³⁴U=（-1.27±2.14）‰（±2σ,n=29）,该结果与国际上不同实验室的测量值在误差范围内一致。U/Th内用标准样品MFT（±2σ,n=22）的δ²³⁴U、²³⁰Th/²³⁸U放射性活度比和年代平均值分别为（408.2±3.2）‰、1.002±0.003和(124.3±0.5) ka,具有较好的重现性。47个石笋样品的²³⁴U/²³⁸U、²³⁰Th/²³⁸U放射性活度比和²³⁰Th/U校正年代的相对误差（±2σ）分别约为0.6‰、2.4‰和0.5%,与已发表数据在误差范围内吻合。     

基于MC-ICP-MS的稳定铜同位素分析在环境健康研究中的应用进展

铜（Cu）是人体内重要的微量金属元素之一,在许多生命过程中扮演着重要角色;同时,铜在人体内受到严格调控,其稳态与人体生理状态密切相关,许多疾病的发生往往伴随着铜代谢失衡的现象。通过监测铜稳态的细微变化,可以更精准地发现导致人体生理异常变化的因素,特别是环境因素对疾病发生及发展的影响。因此,稳定铜同位素分析在环境健康研究中具有广泛的应用前景。多接收器电感耦合等离子体质谱（MC-ICP-MS）是一种强大的同位素分析质谱方法,具有适用范围广、分析精度高等优点,有效促进了铜同位素分析的发展。本文综述了非传统稳定同位素分馏机理及基于MC-ICP-MS的铜同位素分析方法,总结了铜同位素分析在环境健康研究中的主要应用,并对其前景进行展望。     

加速器质谱测量93Zr的刻度研究

A method of determination for ⁹³Zr/⁹²Zr ratio by multi-collector inductively plasma mass spectrometry (MC-ICP-MS) was described in this paper. A ⁹³Zr/⁹²Zr ratio of (2.75±0.07)×10^－5 was obtained in the original sample for AMS measurement and its relative standard error was 2.5%. Considered the contribute of above-thermal neutron, a calculated ⁹³Zr/⁹²Zr ratio of 2.56×10^－5 was obtained and it was according with measurement of the result. The results showed that it can be used for AMS measurement standards sample preparation. A series 93Zr standards sample for AMS measurement were diluted by irradiated sample with enriched 92Zr.