加速器质谱法测定环境和生物样品中的129I

建立了环境和生物样品中的129I的分析方法,采用碱式灰化、萃取-反萃、沉淀等步骤对环境和生物样品中的碘进行预浓集,用131I[NaI] 为放射性示踪剂优化各分步的制备条件,运用加速器质谱法测定了北京地区松针和干草、青岛地区海藻和海水中的129I/127I.用超热中子活化法测定样品中的稳定碘(即127I)含量.上述松针、干草、海藻和海水样品中的129I/127I分别为8.11×10-9、5.97×10-9、1.70×10-10和6.05×10-10;相应的129I浓度分别为3.22×10-15、1.24×10-14、1.27×10-14 g/g干重和2.30×10-14 g/L.与文献报道值相比,我国与国外同类地区相当甚至更低,比法国和英国乏核燃料后处理厂附近环境中的129I低2～3个数量级,表明我国这些非核设施影响地区的129I处于当今全球环境的本底放射性沉降水平.     

二维液相色谱(SCX/RP)系统的构建及对珠蛋白水解产物的研究

以十通阀为切换接口, 构建了SCX/RP常规柱二维液相色谱系统, 并以珠蛋白水解产物的分析对其加以评价. 样品首先由第一维阳离子交换色谱(Hypersil SCX, 100 mm×4.6 mm I.D.)在pH 4.0的磷酸盐缓冲体系中分离, 洗脱产物进入切换接口, 样品组分被富集在捕集柱(Hypersil BDS C18, 15 mm×4.6 mm I.D.)中, 进一步脱盐后被导入第二维反相色谱(Hypersil BDS C18, 250 mm×4.6 mm I.D.)分离分析. 阳离子交换色谱采用逐步增加盐浓度的12步台阶等度间断方式洗脱, 每次将洗脱产物捕集在捕集柱中进而由反相色谱分析, 实现对第一维洗脱产物的切割转移及第二维分析. 与一维色谱相比, 二维液相色谱系统的分辨率、峰容量也得到提高, 系统峰容量达到2280.     

沉积物中129I不同形态的逐级浸取分离

随着核技术的不断发展,核试验、乏燃料后处理及核电站事故等人类核活动向自然界释放了大量的~(129)I。~(129)I在沉积物中的含量与化学形态分布对揭示其迁移规律和沉降信息有着重要的意义。因此,对于研究沉积物中~(129)I不同形态所需要的合理分离及制备流程就尤为重要。结合太湖湖泊沉积物的特点并通过比较众多沉积物中~(129)I形态的分离流程,提出了改进的逐级浸取流程。在温度、时间不同的实验条件下,对沉积物样品分离出沉积物中~(129)I可交换态、有机结合态、金属氧化物态、残余矿物态四种不同形态,并通过高温热解法及125I示踪计算回收率及损失率。改进后的逐级浸取法能达到90%的提取效率,离子可交换态、有机结合态、金属氧化物结合态的适宜浸取时间和温度分别为4.5h、30℃,4.5h、75℃,5.5h、75℃。流程适用于同类湖底沉积物样品分析。     

沉积物中~(129)I不同形态的逐级浸取分离

随着核技术的不断发展,核试验、乏燃料后处理及核电站事故等人类核活动向自然界释放了大量的~(129)I。~(129)I在沉积物中的含量与化学形态分布对揭示其迁移规律和沉降信息有着重要的意义。因此,对于研究沉积物中~(129)I不同形态所需要的合理分离及制备流程就尤为重要。结合太湖湖泊沉积物的特点并通过比较众多沉积物中~(129)I形态的分离流程,提出了改进的逐级浸取流程。在温度、时间不同的实验条件下,对沉积物样品分离出沉积物中~(129)I可交换态、有机结合态、金属氧化物态、残余矿物态四种不同形态,并通过高温热解法及125I示踪计算回收率及损失率。改进后的逐级浸取法能达到90%的提取效率,离子可交换态、有机结合态、金属氧化物结合态的适宜浸取时间和温度分别为4.5h、30℃,4.5h、75℃,5.5h、75℃。流程适用于同类湖底沉积物样品分析。     

吹扫捕集-气相色谱-质谱法快速测定同序列地下水和土壤中的37种挥发性有机物

建立了吹扫捕集-气相色谱-质谱法(GC-MS)测定同序列地下水和土壤样品中37种挥发性有机物(VOCs)含量的方法.分别采集地下水、土壤样品并封装于40 mL棕色吹扫瓶中,采用全自动固液一体吹扫捕集装置,于20℃吹扫11 min,于250℃脱附1.7 min,于280℃烘烤8 min,将分离后的VOCs利用气相色谱-质...     

二维液相色谱接口的改进及其在蛋白质组学研究中的应用

随着蛋白质组学、本草物质组学等组学概念的提出,所需分析的样品的成分越来越复杂,因此具有强大分离能力的多维液相色谱技术受到人们越来越多的关注。二维液相色谱中第二维的分离性能和速度是整个分离系统性能的关键。基于捕集柱模式,我们采用经特殊设计的流路系统,使得双捕集柱型接口具有预分离的功能。样品从第一维流出以后被富集在捕集柱1的柱头,经过脱盐后,正冲捕集柱,捕集柱1与第二维色谱柱联用对富集的样品进行分离,增加了第二维分离效率。当捕集柱上的样品全部被洗脱到第二维色谱柱上时,捕集柱2已经完成对第一维洗脱液中样品的捕集和脱盐,此时将阀进行切换,捕集柱2与第二维色谱柱直接相连进行洗脱。循环切换捕集柱1和捕集柱2,维持较高的阀切换频率,实现了第二维色谱柱的连续洗脱。因此保证了第二维分离具有较快速度,同时具有较高的分离效率。使用35 mm长捕集柱和十通阀为接口,以弱阴离子交换(WAX)色谱为第一维分离模式,以反相(RP)色谱为第二维分离模式,构建了WAX-RP二维液相色谱系统(2D-LC system)。以小鼠血清为样品对系统进行了初步评价。色谱流出曲线出现了明显的界面现象,这是由于捕集柱流动相中含有的较多盐分流出时的背景吸收造成的。同时,由于界面两侧的流动相黏度不同产生了黏性指进(VF)现象。当第二维色谱柱长度为50 mm时,理论上可将第二维分离效能提高70%。该接口可以应用于多种二维液相色谱模式,适用于蛋白质组学和本草物质组学研究中对于复杂样品的分离分析。     

高温二维液相色谱系统的构建及其评价

在二维液相色谱中, 第二维的分离速度是制约其发展的重要因素. 升高色谱柱温度可以有效降低流动相粘度, 加快溶质在两相间的传质速率, 有效加快分析速度. 以离子交换色谱法(WAX)为第一维分离模式和反相色谱法(RP)为第二维分离模式, 十通阀和两个捕集柱为接口, 通过将第二维色谱柱温度升高到80 ℃和提高流量到3 mL/min, 构建了高温WAX/RP二维液相色谱系统. 以4种标准蛋白的酶解物为样品评价系统的分离性能, 第一维共有33个馏分被捕集并导入到第二维分析, 高温二维液相色谱系统识别出187个色谱峰.     

吹扫捕集-原子荧光光谱与同位素稀释质谱法结合测定海水中痕量汞

建立了吹扫捕集-原子荧光光谱,结合同位素稀释质谱法测定海水中痕量汞的高准确度的分析方法,以HNO3消解样品,通过吹扫捕集、金柱吸附的方式实现痕量汞与高盐基体的分离并进一步富集,与电感耦合等离子体质谱联用,采用同位素稀释质谱法进行准确测定.对影响样品准确测定结果的消解用HNO3体积、消解时间、SnCl2用量、基体影响、本...     

吹扫捕集–气相色谱–质谱法测定水上玩具中65种挥发性有机物的迁移量

建立吹扫捕集–气相色谱–质谱法测定水上玩具中65种挥发性有机物迁移量。以超纯水为介质,模拟玩具的实际使用环境,在特定条件下进行迁移试验,迁移液直接采用吹扫捕集方式进样,通过气相色谱分离,质谱定性,内标法定量,以方法检出限、线性相关系数、准确度和精密度为考察指标进行方法学验证。65种挥发性有机物的检出限为0.2～1.6 μg/L,其质量浓度在5.00～200 μg/L范围内相关系数均不小于0.998,样品加标回收率为75.4%～105%,测定结果的相对标准偏差不大于20%(n=7)。该方法简便、快速、灵敏度高,适用于玩具中挥发性有机物迁移量的测定。     

毛细管气相色谱法同时测定挥发性卤代烃及氯代苯

本文报道用毛细管气相色谱法同时测定挥发性卤代烃及氯代苯。采用吹扫-捕集法富集样品，应用大口径厚液膜弹性石英毛细管柱分离，方法操作简便，准确度和重现性好，且受水样基体干扰小。     

Immobilization of fission iodine by reaction with insoluble natural organic matter

Iodine-129 is a fission product and highly mobile in the environment. Along with other stable isotopes of iodine, ¹²⁹I is released during reprocessing of nuclear fuel and must be trapped to prevent the release of radioactivity to the environment. Past studies have provided evidence that iodine can become associated with natural organic matter (NOM). This research explores the use of NOM (sphagnum peat and humic acid) to sequester iodine from the vapor and aqueous phases. NOM-associated iodine may be stable for geological storage. NOM-sequestered iodine can be recovered by pyrolysis to prepare target materials for transmutation. The nature of the NOM-iodine association has been explored.     

Iodine separation procedure for the determination of129I and127I in soil by neutron activation analysis

A radiochemical neutron activation analytical method for the determination of¹²⁹I and¹²⁷I in soil samples was studied. Iodine was separated from the sample prior to the irradiation by volatilization, i.e. by combustion of the sample and trapping of the iodine in an alkaline solution together with a reducing agent. This method enables one to digest samples containing up to 100 g dry matter. The chemical yield was mostly more than 90%. After irradiation the iodine fraction was further purified by solvent extraction. The detection limit of the¹²⁹I/¹²⁷I ratio was 1×10^–9.     

Determination of129I and127I in human thyroid blocks containing mercury as a preservative

A solvent extraction techniques has been developed to separate iodine from mercury contained in thyroid tissues for the determinations of¹²⁹I and¹²⁷I in human thyroid blocks by neutron activation analysis. The tissue samples are digested with a mixture of 5 ml HCl and 1 ml HNO₃ in a round-bottomed flask fitted with a condenser running with cold water to avoid any loss of iodine. Iodine is extracted into 0.1 M dihexyl sulfide solution in xylene leaving the majority of the mercury in the aqueous phase. Iodine is adsorbed on activated charcoal packed in quartz tubes either by heating the xylene containing iodine in the presence of oxygen or by heating the aqueous solution obtained after back extracting iodine from xylene using a saturated sulfur dioxide solution. Iodine is desorbed from the charcoal and trapped into a quartz ampule which is sent for neutron activation.     

Distribution and behavior of long-lived radioiodine in soil

The concentration of¹²⁹I in soil in Japan was determined by neutron activation analysis. For the activation analysis, pre-irradiation chemical separation of the iodine was carried out by acid decomposition and distillation and post-irradiation treatment was performed by ion exchange and solvent extraction. The concentration of stable iodine and¹³⁷Cs were also determined and compared with the behavior of¹²⁹I in soil.Soil samples from Ibaraki, Fukui, Fukushima, and Nagasaki Prefectures were analyzed and¹²⁹I was detected in amounts ranging from 10^–7 to 10^–5 Bq/g soil in uncultivated surface soil. There are apparently small variations in the¹²⁹I concentrations in each of the regions analyzed.From depth profile studies in sandy soil, the iodide form of¹²⁹I was found to migrate downward at a relatively rapid rate while other species remain longer in the surface soil.     

Assessment of Iodine in the Diet of People Living Around a Nuclear Reprocessing Plant: Dose-Related Consequences of an Intake of 129I

It is important that in radioiodine dosimetry for low levels of daily intake, allowance must be made for the normal daily intake of stable iodine. This intake varies from one region to another, and variations are observed from one person to the next within a region, depending on eating habits. Measuring iodine in the urine over 24 hours can indirectly assess these variations. Analysis of the total iodine in the urine was carried out for 69 French people living in a temperate maritime region or in mainland France. This study justifies individual assessment of the coefficient of iodine transfer to the thyroid by means of this survey based on the urinary iodine analysis. The consequences for man of the release of ¹²⁹I around a nuclear reprocessing plant were analyzed by applying the methodology published previously by the authors. A software program based on the iodine biokinetic model recommended by the ICRP was used to calculate the daily urine excretion of ¹²⁹I for five different diets of total iodide in a ratio of 10^-4 for ¹²⁹I/¹²⁷I. This model makes it possible to set a practical detection limit of 20 mBq (0.003 µg). This approach is important from a practical point of view for health physicists involved in routine monitoring of workers in the nuclear field and members of the public exposed to radioiodine released into the environment.     

Occurrence,evolution and degradation of heavy haze events in Beijing traced by iodine-127 and iodine-129 in aerosols

Heavy haze events have become a serious environment and health problem in China and many developing countries, especially in big cities, like Beijing. However, the factors and processes triggered the formation of secondary particles from the gaseous pollutants are still not clear, and the processes driving evolution and degradation of heavy haze events are not well understood. Iodine isotopes (¹²⁷I and ¹²⁹I) as tracers were analyzed in time series aerosol samples collected from Beijing. It was observed that the ¹²⁷I concentrations in aerosols peaked during the heavy haze events. The conversion of gaseous iodine to particular iodine oxides through photochemical reactions provides primary nuclei in nucleation and formation of secondary air particles, which was strengthened as the external iodine input from the fossil fuel burning in the south/southeast industrial cities and consequentially induced heavy haze events. Anthropogenic ¹²⁹I concentrations peaked during clean air conditions and showed high levels in spring and later autumn compared to that in summer. ¹²⁹I originated from the direct air discharges and re-emissions from contaminated seawaters by the European nuclear fuel reprocessing plants was transported to Beijing by the interaction of Westerlies and East Asian winter monsoon. Three types of mechanisms were found in the formation and evolution of heavy haze events in Beijing by the variation of ¹²⁷I and ¹²⁹I, i.e., iodine oxides intermediated secondary air particles, dust storm and mixed mode by both secondary air particles and dust storm induced processes.     

Chemical and nuclear interferences in neutron activation of129I and127I in environmental samples

A combination of neutron activation and gamma-ray coincidence counting technique is used to determine the concentration of both long-lived fission produced¹²⁹I and natural¹²⁷I in environmental samples. The neutron reactions used for the activation of the iodine isotopes are¹²⁹I(n, )¹³⁰I and¹²⁷I(n, 2n)¹²⁶I. Nuclear interferences in the activation analysis of¹²⁹I and¹²⁷I can be caused by production of¹³⁰I or¹²⁶I from other constituents of the materials to be irradiated, i.e. Te, Cs and U impurities and from the¹²⁵I tracer used for chemical yield determination. Chemical interferences can be caused by¹²⁹I and¹²⁷I impurities in the reagents used in the pre-irradiation separation of iodine. The activated charcoals used as iodine absorbers were carefully cleaned. Different chemical forms of added¹²⁵I tracer and¹²⁹I and¹²⁷I constituents of the samples can cause different behaviour of¹²⁵I tracer and sample iodine isotopes during pre-irradiation separation of iodine. The magnitude of the nuclear and chemical interferences has been determined. Procedures have been developed to prevent or control possible interferences in low-level¹²⁹I and¹²⁷I activation analysis. For quality control a number of biological and environmental standard samples were analyzed for¹²⁷I and¹²⁹I concentrations.     

A study on the association of two iodine isotopes,of natural127I and of the fission product129I,with soil components using a sequential extraction procedure

Sequential extraction techniques have been utilized in order to investigate the degree of binding or association of natural iodine¹²⁷I and the radioactive iodine isotope¹²⁹I with soil components. The results indicate that only a small fraction of natural iodine (2.5–4%) but a large fraction of the recently added radioactive¹²⁹I (38–49%) is water-soluble. The other forms of iodine which were determined for both iodine isotopes were exchangeable iodine, iodine bound to metal-oxides and iodine bound to organic matter.     

Ultra-trace determination of iodine in sediments and biological material using UV photochemical generation-inductively coupled plasma mass spectrometry

Several sample preparation techniques have been evaluated for the determination of iodine using UV-photochemical generation-quadrupole inductively coupled plasma mass spectrometry. Thermal decomposition of samples at 1000 °C followed by capture of the liberated iodine in dilute acetic acid permitted subsequent UV-photochemical generation of a volatile iodine species that serves to enhance sensitivity 25-fold over conventional solution nebulization, delivering reagent blank detection limits of 8.75 pg g^{–1 127}I and 0.075 pg g^–1 129I for solid samples (400 mg test mass). The methodology was validated through determination of total iodine in several Standard Reference Materials, including NIST 1572 Citrus leaves, NIST 1549 Non-fat milk powder, NIST 1566a Oyster tissue and NIST 2709 San Joaquin Soil. Liberation of iodine from samples and its collection as well as photochemical generation were quantitative, permitting calibration to be achieved using standards prepared in dilute acetic acid.     

k 0-RNAA used in determination of 129I in a mixed resin sample

A k ₀-RNAA procedure was developed to determine ¹²⁹I in a mixed resin sample. CH₄ extraction and (NH₄)₂SO₃ back-extraction were used to separate ¹²⁹I in ashed samples. The ¹²⁹I target sample for irradiation in the reactor was prepared by heating the (NH₄)₂SO₃ back-extraction solution to reduce its volume and then to dry it in a quartz ampoule. No MgO and LiOH were needed during the target sample preparation. After irradiation, the nuclide ¹³⁰I was purified by combining hydrated antimony pentoxide column and CH₄ extraction separations. A k-factor was determined for the reaction of ¹²⁷I (n, 2n) ¹²⁶I and used for iodine chemical yield determination. The apparent ¹²⁹I concentrations of five nuclear reaction interferences were calculated. The relative standard deviation of three ¹²⁹I determinations was found to be 3.5 %. The ¹²⁹I content in the analyzed resin was found to be 1.36 × 10^?9 g/g (8.63 × 10^?3 Bq/g) with a relative uncertainty of 9.1 %. The detection limit of ¹²⁹I was calculated to be 7.4 × 10^?13 g (4.7 × 10^?6 Bq) in a k ₀-RNAA of a blank sample.