水体污染检测用锡质量控制标准物质研究

研制国家级水质锡质量控制用标准物质,作为锡分析检测的质量控制标准。依据国家标准样品工作导则要求,制备锡标准物质;采用原子荧光光谱法对样品进行均匀性和稳定性研究;以多个实验室协作分析定值的统计结果确定标准值,并进行不确定度评估。经检测锡标准物质均匀性良好,稳定性可达24个月以上;样品量值准确,与美国同种标准物质进行比对具有可比性。研制的锡标准物质符合国家标准物质的技术要求,可用于水质锡元素检测的质量控制、分析方法研究以及分析实验室能力验证等方面。     

水质监测锂环境标准样品研究

针对我国缺少国家级锂环境标准样品的情况,研究介绍锂环境标准样品的研制方法。锂环境标准样品采用重量法制备,用原子吸收法对样品进行均匀性和稳定性研究;多家实验室分别采用AAS、ICP-AES、AFS、ICP-MS协作分析定值后数理统计确定标准值,并进行不确定度评估。结果表明:锂环境标准样品的均匀性良好,稳定性符合要求;与美国同种标准物质具有可比性,可用于仪器校准、分析方法的评价与验证、实验分析的质量控制和能力验证等方面。     

薯蓣皂素标准物质的研制

按照JJF 1006——1994《一级标准物质技术规范》的要求,建立薯蓣皂素标准物质的研制方法。采用IR、UV、MS和NMR等方法对薯蓣皂素标准物质进行定性分析,以高效液相色谱方法进行均匀性和稳定性检验,通过8家实验室的联合定值,完成结果的数据分析。结果表明:该标准物质的均匀性和稳定性良好,定值结果为98.9%,置信度为95%的不确定度为0.2%。研制出的标准物质可用于薯蓣产品的检测和质量控制。     

腹泻性贝类毒素基体标准物质的研制

为了保证小鼠生物法、荧光衍生法、质谱法等对腹泻性贝类毒素检测结果的准确、可靠和可比,以紫贻贝为基体,采用添加法研制了一种含腹泻性贝类毒素软海绵酸(OA)的冻干粉形式的贝类毒素基体标准物质.采用LC-MS/MS法,以多家定值的方式对标准物质中的OA进行定值.均匀性检验结果表明该样品均匀,短期稳定性和6个月的稳定性考察表明样品稳定性良好.经过对影响定值结果的称样量、定容、校准物、校准曲线等因素的考察,进行不确定度评定,标准物质中OA的含量及不确定度为2.96土0.50μgOA/g(k=2).该标准物质可以用于腹泻性贝类毒素检测过程的方法验证与质量控制等.     

苹果醋中安赛蜜、山梨酸和日落黄成分分析标准物质的研制

研制了苹果醋中安赛蜜、山梨酸和日落黄成分分析标准物质,优化并建立了高效液相色谱-二极管阵列检测器（HPLC-DAD）方法对目标物分析测量。标准物质的均匀性经单因素方差分析显示均匀,稳定性经线性回归趋势分析表明在7个月内量值稳定。定值方式采用多家实验室（9家）合作定值。 标准值及扩展不确定度(k=2):安赛蜜(141±8)mg/kg, 山梨酸(259±12)mg/kg, 日落黄(8.45±0.33)mg/kg。     

西洋参中人参皂苷Rg1、Re、Rb1基体标准物质的研制

建立高效液相色谱法和高效毛细管电泳法,对研制的西洋参基体标准物质中人参皂苷Rg₁、Re、Rb₁含量进行准确定值,同时考察了样品的均匀性、稳定性和样品的最小取样量,最后对标准物质的不确定度进行了评定。评定结果为人参皂苷Rg₁、Re、Rb₁含量分别为（1.72±0.14）mg/g、（15.3±1.5）mg/g、（25.8±2.8）mg/g,相对扩展不确定度分别为8.4％、10％、11％,可为西洋参的质量控制提供依据。     

熔体质量流动速率的测定能力验证研究

利用自制的聚乙烯样品来评价各参加实验室的熔体质量流动速率的检测能力.采用单因子方差分析法对制备的聚乙烯样品进行均匀性、稳定性检验;以各参加实验室结果的中位值作为测试熔体质量流动速率的指定值,以标准化四分位距(NIQR)作为变动性度量值(目标标准偏差),采用Z比分数评价各参加实验室的测试结果.研究表明,所制备的能力验证聚乙烯样品符合均匀性、稳定性要求,本项目所采用的方法可评估各实验室对熔体质量流动速率的检测能力.     

金精矿中银量测定循环比对结果分析

为了提升各实验室检测金精矿中银量的能力,组织了14家实验室对金精矿样品进行检测,采用F检验法和■0.3σ准则法分别考察制备样品的均匀性和稳定性,通过Z比分数评价各实验室的测试结果。实验结果表明,样品具有良好的均匀性和稳定性,符合循环比对样品的要求,各实验室的Z比分数均小于2,结果满意,说明实验室具备检测金精矿中银量的能力。     

白藜芦醇标准样品的研制

依据GB/T 15000——2008标准样品工作导则,研制白藜芦醇标准样品。采用高速逆流色谱方法制备白藜芦醇样品,通过UV、IR、MS和NMR等方法对白藜芦醇样品进行结构鉴定,并进行均匀性、稳定性检验。采用8家实验室对制备的白藜芦醇样品进行联合定值,并对定值结果进行数据分析。白藜芦醇标准样品均匀性和稳定性良好,其定值结果为99.79%,置信度95%的扩展不确定度为0.66%。所制备的白藜芦醇样品满足标准样品工作导则的要求,可用于有关白藜芦醇检测方法的校正和相关产品的质量控制。     

碳黑比表面积标准物质的研制

选择商品化的碳黑作为比表面积标准物质候选材料,利用交叉缩分的方法对碳黑样品进行分装。经均匀性、稳定性(18个月)检验,碳黑标准物质样品具有良好的均匀性和稳定性。按照国际公认的氮气物理吸附BET方法,联合测量能力经确认过的8家实验室对碳黑标准物质样品进行定值(104.6、29.9、8.96 m2/g)。与国内外同类标准物质比较表明:研制的3种碳黑比表面积标准物质的相对不确定度(2.1%、2.3%和3.2%)达到国际同类标准物质的先进水平。     

Carbon nanomaterials based on plant biopolymers as radionuclides sorbent

Abstract

The technogenic human activities associated with the operation of nuclear power facilities lead to the contamination of natural water bodies and soils with radioactive substances, including heavy radionuclides, such as uranium and thorium. Purification of natural water bodies is a pressing environmental issue. A study of the adsorption capacity for heavy U²³⁸ and Th²³² radionuclides by the samples of new carbon nanomaterials was conducted. Nanocarbon materials was synthesized based on vegetal polymers, such as technical lignin, starch and from lignocellulosic material—the bark. It was established that the investigated samples have different sorption indices in relation to radionuclides, which is determined by their chemical composition, as well as by the surface-capillary properties of carbonized materials. It is shown that the content of mobile and fixed forms of radionuclides on the investigated sorbents are significantly different. High sorption capacity of the carbonated lignin sample with respect to uranium are shown. A sample of nanocarbon materials synthesized based on the lignocellulosic complex of the bark exhibits high sorption properties in relation to thorium. The possibility of using the carbonic nanomaterial as the sorbents of radionuclides is shown.     

Alpha/Beta liquid scintillation spectrometry in surveying Finnish groundwater samples

Natural radionuclides have been surveyed in Finnish groundwaters using alpha/beta liquid scintillation spectrometry since the late 1980s. Until now, gross alpha and gross beta have been determined in more than 11 000 samples by this technique, which has created significant savings in labor costs compared to previous gross alpha and gross beta methods based on using ZnS scintillation counters and low-background β-ray counters. The sample preparation method is now much easier and large samples series can be counted automatically. The main savings are, however, achieved by measuring the α-and β-ray spectra on a low-background liquid scintillation spectrometer, which provides valuable information on the occurrence of the long-lived α-emitting (²³⁸U and ²³⁴U, ²²⁶Ra and ²¹⁰Po) or β-emitting (⁴⁰K, ²¹⁰Pb, and ²²⁸Ra) nuclides in water. The α-ray spectrum allows calculation of the uranium and radium contents in most groundwater samples quite accurately, and thus expensive radiochemical analyses are avoided. The concentrations of radon, gross alpha, and gross beta are determined from all drinking water samples delivered for radioactivity measurements. The gross alpha and gross beta are mainly used to screen whether the levels of long-lived nuclides exceed the limits set in the regulations. Published in Russian in Radiokhimiya, 2006, Vol. 48, No. 6, pp. 544–550. The text was submitted by the author in English. Reported at the 7th Russian-Finnish Symposium on Radio-chemistry (St. Petersburg, November 2005).     

Radioactivity in soil from the city of Kavadarci (Republic of Macedonia) and its environs

The activity concentrations and distribution of natural and anthropogenic radionuclides in soils from the city of Kavadarci, Republic of Macedonia, and its environs were investigated. The purpose of the study, the first of this kind in this region was to evaluate the environmental radioactivity and radiological health hazard, as well as to determine the connection between the concentration of natural radionuclides and the geology of the terrain. A total of 45 surface soil samples were collected from evenly distributed sampling sites. Gross alpha and gross beta activity measurements were made using a gas flow proportional counter, while the activity concentrations of gamma emitting radionuclides were measured using a high purity germanium detector. The average activity concentrations of ??K, 22?Ra, 232Th and 13?Cs were found to be 546±118, 38.8±14.6, 43.7±18.4 and 41.5±40 Bq kg?1, respectively. The mean values of gross alpha and gross beta activities were 522±192 and 681±146 Bq kg?1. The mean total absorbed dose rate in air calculated from the concentration of the natural radionuclides was 67.1±20.9 nGy h?1, and the corresponding annual effective dose rate outdoors was 0.082±0.026 mSv y?1. The results of the analysis show strong correlation between the abundance of the natural radionuclides in soils and their geological origin.     

Characterization and remediation of soils contaminated with uranium

Environmental contamination caused by radionuclides, in particular by uranium and its decay products is a serious problem worldwide. The development of nuclear science and technology has led to increasing nuclear waste containing uranium being released and disposed in the environment. The objective of this paper is to develop a better understanding of the techniques for the remediation of soils polluted with radionuclides (uranium in particular), considering: the chemical forms of uranium, including depleted uranium (DU) in soil and other environmental media, their characteristics and concentrations, and some of the effects on environmental and human health; research issues concerning the remediation process, the benefits and results; a better understanding of the range of uses and situations for which each is most appropriate. The paper addresses the main features of the following techniques for uranium remediation: natural attenuation, physical methods, chemical processes (chemical extraction methods from contaminated soils assisted by various suitable chelators (sodium bicarbonate, citric acid, two-stage acid leaching procedure), extraction using supercritical fluids such as solvents, permeable reactive barriers), biological processes (biomineralization and microbial reduction, phytoremediation, biosorption), and electrokinetic methods. In addition, factors affecting uranium removal from soils are furthermore reviewed including soil characteristics, pH and reagent concentration, retention time.     

Distribution of uranium in Dounreay workers due to uptake from the environment

At Dounreay, there are a number of facilities in which the main radiological hazard is the intake of uranium. The hazard is managed through the implementation of controls and contamination surveys in order to reduce the risk of intake. In order to provide reassurance that radiological significant intakes are not taking place, a routine urine sample programme is in place. As well as being exposed to work place sources of uranium workers are also exposed to the intake of uranium from foodstuffs and water, which are not associated with their work at Dounreay. In order to characterise the intake of the radionuclides from the environment, urine samples were collected from a group of Dounreay personnel who are not exposed to uranium in their workplace. The distribution of the uranium isotopes 234U, 235U and 238U has been assessed for these workers. The distributions will be used to assess the likelihood of uranium detected in urine for a uranium worker being due to an intake in the workplace. The best match to distributions of 234U and 238U was found to be a combination of normal and lognormal distributions.     

Evaluation of occupational exposure to naturally occurring radioactive materials in the Iranian ceramics industry

Zircon contains small amounts of uranium, thorium and radium in its crystalline structure. The ceramic industry is one of the major consumers of zirconium compounds that are used as an ingredient at ～10-20 % by weight in glaze. In this study, seven different ceramic factories have been investigated regarding the presence of radioactive elements with focus on natural radioactivity. The overall objective of this investigation is to provide information regarding the radiation exposure to workers in the ceramic industry due to naturally occurring radioactive materials. This objective is met by collecting existing radiological data specific to glaze production and generating new data from sampling activities. The sampling effort involves the whole process of glaze production. External exposures are monitored using a portable gamma-ray spectrometer and environmental thermoluminescence dosimeters, by placing them for 6 months in some workplaces. Internal routes of exposure (mainly inhalation) are studied using air sampling, and gross alpha and beta counting. Measurement of radon gas and its progeny is performed by continuous radon gas monitors that use pulse ionisation chambers. Natural radioactivity due to the presence of 23?U, 232Th and ??K in zirconium compounds, glazes and other samples is measured by a gamma-ray spectrometry system with a high-purity germanium detector. The average concentrations of 23?U and 232Th observed in the zirconium compounds are >3300 and >550 Bq kg?1, respectively. The specific activities of other samples are much lower than in zirconium compounds. The annual effective dose from external radiation had a mean value of ～0.13 mSv y?1. Dust sampling revealed the greatest values in the process at the powdering site and hand weighing places. In these plants, the annual average effective dose from inhalation of long-lived airborne radionuclides was 0.226 mSv. 222Rn gas concentrations in the glaze production plant and storage warehouse were found to range from 10 to 213 Bq m?3. In this study, the estimated annual effective doses to exposed workers were <1 mSv y?1.     

Effect of solution pH on the synthesis of the YBa2Cu4O8 superconductor via an EDTA solution process

High critical temperature, Tc, YBa2Cu4O8 superconducting oxides have been prepared by a solution technique using ethylenediaminetetraacetic acid (EDTA) as complexing agent. The use of an appropriate complexing agent leads to complete mixing of the Y3+, Ba2+ and Cu2+ cations, and thus facilitates formation of YBa2Cu4O8 at a lower temperature. The effect of pH on the homogeneity of samples is discussed. The superconducting YBa2Cu4O8 sample with Tc = 80 K was obtained after heat treatment at 820°C. Characterization of the sample by X-ray diffraction (XRD), thermal analysis, scanning electron microscopy (SEM), electron-probe microanalysis (EPM), electrical resistivity, magnetic susceptibility and other spectroscopic analyses are reported. This revised version was published online in November 2006 with corrections to the Cover Date.     

Physical Properties and Electrochemical Performance of LiNixMn2-xO4 Cathode Materials Prepared using a Precipitation Method

To improve the cycle performance of spinel LiMn204 as the cathode material of 4 V class Li secondary batteries, LiNixMn2-xO4 （x=0-0.3） samples were prepared using a simple precipitation method, and the effects of Ni doping on the physical properties and electrochemical performance of the samples were investigated using various methods. All LiNixMn2-xO4 （x=0-0.3） compounds show a single spinel phase, and the lattice parameter （a）, the unit cell volume （v） and particle size decrease with increasing Ni content. The results of the electrochemical experiments showed that the initial charge-discharge capacity of LiNixMn2-xO4 samples in the 3.0-4.4 V range decreases with increasing Ni content except for pure LiMn2O4; however, the capacity in the 4.4-4.9 V range increases with the increasing Ni content. For spinel samples Ni substitution can contribute to the improvement of their cycle performance due to the formation of the stronger Ni-O bond, homogeneous morphology, and sub-micron sized particles, and the sample with x=0.05 has larger peak currents, higher initial capacity and better cycling capability due to its lower electrochemical and diffusion polarization than those of other samples.     

Analysis of naturally produced technetium and plutonium in geologic materials

In uncontaminated natural materials, plutonium and technetium exist exclusively as products (daughters) of nuclear reactions in which uranium is the principal reactant (parent). Under conditions of chemical stability over geologic periods of time, the relative abundances of daughter and parent elements are fixed by the rates of nuclear reactions and the decay of the daughter radionuclide. The state of this nuclear secular equilibrium condition is the primary basis of the geochemical study of these elements in nature. Thus, it is critical that nuclear parent and daughter abundances are measured in the same sample. We have developed a quantitative procedure for measuring subpicogram quantities of plutonium and technetium in gram quantities of geologic matrices such as uranium ores. The procedure takes advantage of the aggressive properties of sodium peroxide/hydroxide fusion to ensure complete dissolution and homogenization of complex materials, the precision provided by isotope dilution techniques, and the extreme sensitivity offered by thermal ionization mass spectrometry. Using this technique, a quantitative aliquot can be removed for uranium analysis by isotope dilution thermal ionization mass spectrometry or α spectrometry. Although the application of the procedure is unique, the analytical concepts may find more general application in studies of environmental contamination by nuclear materials. To assess the precision and accuracy of the analytical results, blanks and standards were analyzed routinely for a 1-year period to ensure quality control of our sample analyses. The average technetium blank is 5 ± 4 fg (n = 8), and that for plutonium is 0.17 ± 0.15 pg (n = 7). Thus, the detection limit for technetium (defined as 3 times the standard deviation of the average blank) is 11 fg, and that for plutonium is 0.44 pg. To assess the procedural precision, Canadian Reference Material BL-5 was analyzed routinely with samples. The results of seven replicate analyses for technetium in this standard reference material yield a technetium concentration of 59.0 fg/g, with a remarkably small standard deviation of 0.6 fg, 1.0% of the average value. The results of six replicate analyses for the concentration of plutonium in BL-5 give 1.012 pg/g, with an equally small standard deviation of 0.016, 1.6% of the average value. No direct measure of accuracy can be done on the technetium or plutonium analyses, because no standard reference material exists for these elements. To help constrain the accuracy of our measurements, equilibrium technetium/uranium and plutonium/uranium abundances were calculated using the nuclear reaction code MCNP. For technetium, such calculations are relatively insensitive to variations in model parameters, and measurements fall within a 21% high/low bias. For plutonium, the calculations are very sensitive to model parameters and hence inherently less precise. Indirectly, spike and isotope mix calibrations made from weighted quantities of certified isotopes (both technetium and plutonium) can be used to determine the bias of the measurement system for these elements. These calibrations show that the measurement system is biased by no more than ±1.5%.     

浸渗掺杂技术在制备半透明氧化铝陶瓷中的应用

实验证实了可以使用液相前驱体浸渗技术来均匀引入添加剂和制备半透明氧化铝陶瓷。首先在不同的浸渗条件下使用硝酸钇的水溶液浸渗了预烧的氧化铝坯体。通过线扫描表征了沿坯体厚度方向上的钇元素分布情况, 发现当试样厚度更小, 溶液浓度更低时, 钇元素分布更加均匀, 而且引入量的调控也更为精确。通过假设气孔被溶液完全填充, 提出了预测浸渗引入理论量的公式。最后使用浸渗方法制备了透明氧化铝陶瓷, 发现与球磨制备的样品相比, 浸渗制备的材料显微组织更为均匀, 透光性能也更好。