建材样品放射性含量测量比对结果分析

目的 通过参加全国建材样品中放射性含量分析比对,验证本实验室检测能力,进行检测质量控制。方法 按照日常检测所使用的方法对比对组织者提供的盲样进行检测,将结果上报进行比对分析。结果 本实验室测量值相对偏差范围为-2.18%~-7.55%,均在合格范围内。结论 仪器性能良好、检测数据合格。     

基于HPGe谱仪的土壤介质放射性样品测量比对分析

目的 为了检验和提高γ谱仪分析性能和测量准确性,本实验室参加了由中国辐射防护研究院组织的土壤介质放射性样品测量比对活动。方法 采用效率曲线法,利用低本底高纯锗γ谱仪对一个模拟土壤样品进行测量比对,通过相对偏差、Z检验、U检验、准确度和精确度等多种检验方法对测量结果进行了分析讨论。结果 此次比对数据的结果可以接受。结论 验证了我实验室的检测方法可靠,质控措施可行,检测结果可信。     

2011年参加全国放射卫生检测能力考核结果分析

目的 检验本实验室放射卫生检测能力和水平。方法 按照组织者比对方案要求,实验室对不同的比对样进行测试,得出各比对样品的测量值,分析测量值与参考值的相对偏差,符合组织者要求为比对合格。结果 4项比对结果均合格。结论 本实验室检测能力和水平满足放射卫生技术服务的要求。     

2009-2016年高纯锗γ能谱分析方法比对结果分析

目的 保证高纯锗γ能谱仪对样品中放射性核素含量检测的准确度，不断提高实验室放射性核素的检测分析水平。方法 连续参加由中国疾病预防控制中心组织的全国放射性核素γ能谱分析能力比对考核，对2009-2016年的比对测量结果进行分析。结果 本实验室2009-2016年比对考核结果均为合格，25个测量结果的相对偏差范围在-17.58%至13.06%之间。结论 本实验室使用的放射性核素的测量分析方法正确，出具的检测报告准确可信。     

2014年参加全国γ能谱分析质量控制比对结果

目的 总结2014年放射性核素γ能谱分析质量控制比对,验证放射性核素分析方法的可靠性。方法 采用国家标准,利用γ能谱仪分析土壤比对样品中²⁰⁸Tl、¹³⁷Cs、²²⁸Ac和⁴⁰K放射性核素的含量。结果 我所实验室比对样品的测量值相对校准值偏差均< 10%,各核素比对结果无论是准确度还是精确度均满足比对要求,判定结果为"合格"。结论 比对结果证明,我所γ能谱测量系统的质量保证体系和质量控制技术是完善和有效的,放射性核素的测量分析方法、数据的处理方法也是可靠的。     

离子吸附型稀土富集物分析的现状与展望

目的 总结我国特有离子吸附型稀土富集物研究现状,设想未来研究思路。方法 根据各离子吸附型稀土富集物的化学构成及放射性变化特征。结果 对已有分析结果进行排列比较,发现其中某些富集物的放射性变化规律和分布比较特殊。结论 应发挥我国稀土资源优势,深入开展相关研究,揭示其中的科学问题。     

土壤中90Sr测量的实验室间比对结果

目的 检验参比单位土壤中⁹⁰Sr的分析能力,以提高各单位的检测水平和测量数据准确度。方法 组织全国辐射环境监测实验室开展土壤中⁹⁰Sr的分析能力比对。结果 参加本次比对有20个实验室,比对结果可以接受的占80%,不可以接受的占20%。结论 比对整体结果良好。但土壤中⁹⁰Sr的分析仍存在一些问题,需要进一步研究。     

土壤样品γ能谱测量中日比对总结

目的 检验和提高γ能谱测量分析技术及质量保证措施。方法 日本JCAC,中国RMTC和我实验室分别对两个土壤样品中的⁴⁰K、²⁰⁸Tl、²¹⁴Bi、²¹⁴Pb、²²⁸Ac和¹³⁷Cs6个核素进行独立测量分析和比对。结果 我实验室对两个样品的测量值相对于总体平均值的最大偏差为4.1%,低水平¹³⁷Cs测量值的最大偏差为3.6%,均满足比对要求。结论 我实验室的检测方法是正确的,质量管理与质量控制体系是完善有效的,结果是可靠的。     

奶粉中60Co、137Cs和90Sr测量的实验室间比对结果

目的 为了提高全国重点辐射环境实验室对食品中⁹⁰Sr和⁶⁰Co、¹³⁷Cs的分析监测水平。方法 组织全国重点辐射环境实验室开展奶粉⁹⁰Sr和⁶⁰Co、¹³⁷Cs标准样品的比对。比对结果采用参考值的相对偏差进行判定。结果 参加奶粉样品⁹⁰Sr比对的实验室8个,相对偏差小于10%,占25%;10%～20%,占12.5%;20%～30%,占62.5%;参加奶粉样品⁶⁰Co、¹³⁷Cs比对的实验室14个,其中⁶⁰Co：相对偏差小于10%,占85.7%;10%～20%,占14.3%;¹³⁷Cs：相对偏差小于10%,占71.4%;10%～20%,占28.6%。整体比对结果可以接受。结论 参加本次比对的实验室,整体比对结果良好。     

某稀土企业环境放射性水平调查

目的 调查和掌握某稀土企业环境放射性水平,为放射性污染防治提供对策。方法 对稀土厂环境γ外照射剂量率、土壤放射性核素比活度、地下水总α、总β比活度进行检测。结果 部分工作场所环境γ外照射明显高于环境本底水平,土壤天然放射性核素比活度略高于江苏省平均值,地下水总α、总β比活度无明显变化。结论 加强对稀土生产企业的管理,降低环境放射性水平。     

Comparing and combining data across multiple sources via integration of paired‐sample data to correct for measurement error

In biomedical research such as the development of vaccines for infectious diseases or cancer, study outcomes measured by an assay or device are often collected from multiple sources or laboratories. Measurement error that may vary between laboratories needs to be adjusted for when combining samples across data sources. We incorporate such adjustment in the main study by comparing and combining independent samples from different laboratories via integration of external data, collected on paired samples from the same two laboratories. We propose the following: (i) normalization of individual‐level data from two laboratories to the same scale via the expectation of true measurements conditioning on the observed; (ii) comparison of mean assay values between two independent samples in the main study accounting for inter‐source measurement error; and (iii) sample size calculations of the paired‐sample study so that hypothesis testing error rates are appropriately controlled in the main study comparison. Because the goal is not to estimate the true underlying measurements but to combine data on the same scale, our proposed methods do not require that the true values for the error‐prone measurements are known in the external data. Simulation results under a variety of scenarios demonstrate satisfactory finite sample performance of our proposed methods when measurement errors vary. We illustrate our methods using real enzyme‐linked immunosorbent spot assay data generated by two HIV vaccine laboratories. Copyright © 2012 John Wiley & Sons, Ltd.     

Results from an inter-laboratory comparison of pneumococcal serotype-specific IgG measurement and critical parameters that affect assay performance

Quantitation of specific IgG to polysaccharides (serotypes) of Streptococcus pneumoniae provides the basis for evaluating vaccine efficacy. Different enzyme-linked immunosorbent assay (ELISA) methods are used internationally, making comparisons between laboratories difficult. We undertook an inter-laboratory comparison between two international laboratories performing serotype-specific IgG ELISAs using a panel of well-characterized serum samples: the Murdoch Childrens Research Institute Pneumococcal Laboratory (Melbourne, Australia) and the Vaccine Immunology Laboratory, National Public Health Institute (Helsinki, Finland). While good agreement was found for the inter-laboratory comparison for most serotypes, differences in ELISA methodology influenced specific IgG measurement. Therefore, use of the World Health Organization (WHO)-based ELISA methods for measurement of serotype-specific IgG is reliable, accurate and provides consistent results between international laboratories.     

Profiles of faecal output of rare earth elements and stable isotopic tracers of iron and zinc after oral administration

The objectives of this study were to confirm the non-absorbability and the reproducibility of faecal excretion kinetics of orally administered rare earth elements, and to investigate the excretion profiles of rare earth elements and stable isotopic tracers of Fe and Zn to establish the extent to which rare earth element markers duplicate the behaviour of isotopic tracers. Two investigations were performed: (1) six healthy subjects consumed a solution containing five rare earth elements in amounts varying from 1 to 10 mg; (2) seven healthy subjects were given a standard solution labelled with Sm marker and (57)Fe tracer, and a meal labelled with Yb marker and (58)Fe and (70)Zn tracers. Individual faecal samples were collected and analysed to determine recoveries of rare earth elements and unabsorbed isotopic tracers. The mean values for recoveries were 94.1 (sd 4.5) % for the five rare earth elements, and 103 (sd 3.0) % and 99.8 (sd 2.8) % for Sm and Yb respectively. For Fe consumed with the solution, excretion kinetics of the rare earth element marker and unabsorbed tracers with cumulative collections of the first two and three faecal samples were identical, but endogenous excretion of Fe was significant in stools collected after the third. For Fe and Zn consumed with the meal, the excretion kinetics for the first two individual faecal samples and composites of sequential outputs were identical. Rare earth elements can be used as markers in studies of measurement of absorption. The dose of tracer required for the measurement of absorption would be reduced proportionally to the reduction of the period of faecal sampling, so that studies with stable isotopes would be more economical, thus enabling epidemiological investigations.     

Performance of laboratories analysing welding fume on filter samples: results from the WASP proficiency testing scheme

This paper emphasizes the need for occupational hygiene professionals to require evidence of the quality of welding fume data from analytical laboratories. The measurement of metals in welding fume using atomic spectrometric techniques is a complex analysis often requiring specialist digestion procedures. The results from a trial programme testing the proficiency of laboratories in the Workplace Analysis Scheme for Proficiency (WASP) to measure potentially harmful metals in several different types of welding fume showed that most laboratories underestimated the mass of analyte on the filters. The average recovery was 70-80% of the target value and >20% of reported recoveries for some of the more difficult welding fume matrices were <50%. This level of under-reporting has significant implications for any health or hygiene studies of the exposure of welders to toxic metals for the types of fumes included in this study. Good laboratories' performance measuring spiked WASP filter samples containing soluble metal salts did not guarantee good performance when measuring the more complex welding fume trial filter samples. Consistent rather than erratic error predominated, suggesting that the main analytical factor contributing to the differences between the target values and results was the effectiveness of the sample preparation procedures used by participating laboratories. It is concluded that, with practice and regular participation in WASP, performance can improve over time.     

自贡市市售食品中稀土元素含量调查

目的调查自贡市市售食品中稀土元素含量。方法所采集食品包括粮食类、蔬菜、菇类、茶叶、蛋类、肉类、鱼类等样品从超市和农贸市场购买,按国家标准方法 GB/T 5009.94-2003《植物性食品中稀土的测定》对样品进行检测。结果样品检测锑、镧、镨、钕、钐等5种稀土含量0.000～1.386 mg/kg,合格率100%。结论抽检的54件自贡市市售粮食类、蔬菜类、肉类、禽蛋类食品中稀土元素含量无1例超标,表明自贡市市售食品稀土元素污染并不严重。     

ICP-MS同时测定土壤中10种稀土元素

初步建立了用HF—HNO3—H3PO4—HClO4体系消解样品,ICP—MS测定土壤中Y、La、Ce、Pr、Nd、Sm、Eu、Tb、Ho、Lu 10种稀土元素的方法。实验表明,方法快速、简便、结果准确、精密度高,适合于土壤中稀土元素的测定。     

Interlaboratory comparison of a reduced volume marine sediment toxicity test method using the amphipod Ampelisca abdita

The U.S. Environmental Protection Agency has standardized methods for performing acute marine amphipod sediment toxicity tests. A test design reducing sediment volume from 200 to 50 ml and overlying water from 600 to 150 ml was recently proposed. An interlaboratory comparison was conducted to evaluate the precision of this reduced sediment volume toxicity test method using the marine amphipod Ampelisca abdita. A negative control and three sediment samples of varying degrees of toxicity ranging from low to high were tested by six laboratories. Complete agreement was reached in rank of relative toxicity for all samples tested by five out of six laboratories. Test acceptability for control survival was achieved by all laboratories, and 69% agreement in classification of the sediments as toxic or nontoxic was documented. Coefficients of variation in all test samples were similar to those reported in other interlaboratory studies using marine amphipods. Results of this study indicate that the reduced sediment volume test using A. abdita is a reliable and precise measure of acute toxicity in marine sediment samples.     

Performance of laboratories measuring silica in the Proficiency Analytical Testing program.

A statistical study was performed on the results reported by laboratories analyzing silica samples in the first 101 rounds of the Proficiency Analytical Testing (PAT) program. Five laboratories participated in the first round of the PAT program in 1972, and participation grew to 130 laboratories before falling to 105 in Round 101. The laboratories use all three of the major methods of analysis: colorimetry, x-ray diffractometry, and infrared spectroscopy. The objectives of the study were to determine bias between methods, the variability associated with the methods, and any changes in bias or variability caused by a number of factors. The colorimetric method has consistently given the lowest results, particularly at higher loadings. X-ray diffractometry results were biased higher than infrared spectroscopy results during one period but not in the following period. Between the two periods, the procedures and materials used to prepare PAT samples changed in a number of ways, but the switch to quartz dust with a smaller particle size is a likely explanation for the bias difference. Generally, silica analyses have improved in precision over time, and this improvement has taken place for all three of the methods. The colorimetric method has shown the poorest precision of the three methods, but, unlike the differences in bias, the differences in precision have diminished considerably over time. Precision estimates from other studies were compared to those from this study to learn more about sources of variability. The largest source of variability, the differences between laboratories, was large even when laboratories used the same method, as they did in a collaborative study of silica methods.     

Interlaboratory comparison for the determination of the soluble fraction of metals in welding fume samples

There is interest in the bioaccessible metal components of aerosols, but this has been minimally studied because standardized sampling and analytical methods have not yet been developed. An interlaboratory study (ILS) has been carried out to evaluate a method for determining the water-soluble component of realistic welding fume (WF) air samples. Replicate samples were generated in the laboratory and distributed to participating laboratories to be analyzed according to a standardized procedure. Within-laboratory precision of replicate sample analysis (repeatability) was very good. Reproducibility between laboratories was not as good, but within limits of acceptability for the analysis of typical aerosol samples. These results can be used to support the development of a standardized test method.