工业锅炉水质分析实验室间比对结果评价

为了解江苏省内各实验室在工业锅炉水质分析检测领域的整体水平,江苏省特检院组织实施了工业锅炉给水中硬度、氯离子、电导率值测定的实验室间比对。本次比对共有20个实验室参加,采用稳健统计技术进行汇总统计,结果表明,实验室满意结果为88.3%,不满意结果占5%,可疑结果占6.7%,其中14家实验室3项检测结果均满意。     

苯乙烯-丁二烯橡胶(SBR)1502实验室间数据比对结果分析

《能力验证规则》CNAS-RL02:2007中明确规定,申请认可的实验室和已经通过认可的实验室要证明其在该领域具有的检验能力,参加能力验证、测量审核、与权威机构比对以及多家实验室间数据比对等系列质量活动是必经之路。在合成橡胶行业通过国家认可实验室较少,组织能力验证活动比较困难,为了满足合成橡胶行业有关生产企业及相关实验室的要求,国家合成橡胶质检中心牵头组织苯乙烯-丁二烯橡胶(SBR)1502产品全项分析实验室间数据比对。数据比对结果采用稳健统计技术进行了统计和分析,所有参加比对的实验室代表了该行业的测试水平。生胶门尼粘度、灰分、混炼胶门尼粘度和50 min 300%定伸应力等测试项目的测定结果较理想;挥发份、25 min 300%定伸应力、35 min 300%定伸应力、35 min拉伸强度和35 min扯断伸长率等测试项目出现的问题相对较多,均有两个以上实验室出现可疑值或离群值;部分实验室尚缺乏化学分析测试能力,应加强相关内容的培训,补充实验仪器的配置,积极参与实验室间比对,不断提高实验室化学分析测试水平。     

液体化工产品结晶点的测定能力验证及结果分析

我单位开展了液体化工产品结晶点测定的能力验证项目,对参加实验室液体化工产品的结晶点的测试能力进行了对比和评价。采用单因子方差分析法和t检验法对考核样品的均匀性和稳定性进行检验,结果证明样品的均匀性和稳定性均符合要求。对实验室提交的结果进行稳健统计,以Z比分数值评价各实验室的测定结果,并绘制Z比分数值柱状图。参加的18家实验室中,共有17家实验室获得了满意结果,占比为95%,仅1家实验室结果不满意,占比5%。此次能力验证正确客观的评价了各实验室结晶点测定项目的检测能力,有助于提升参加实验室业务水平。     

沥青针入度测定的能力验证

为了解和提高国内实验室对沥青针入度测定的检测技术水平,能力验证提供者(CNAS PT0031)承担了中国国家认证认可监督管理委员会的沥青针入度测定的能力验证活动,有22个省、市、自治区共97家实验室参加。介绍了沥青针入度测定能力验证计划的样品制备、均匀性和稳定性检验、以及基于稳健评定的结果统计和分析等实施过程,对各实验室采用的针入度测试标准进行了统计和分析,提出了针入度测定的技术建议。能力验证计划统计表明,满意的实验室有85家,占反馈总数的87.6%。     

化学试剂甲苯中水分含量测定的能力验证

为了解和提高国内实验室对液体化学试剂水分含量的检测技术水平,能力验证提供者(CNAS PT0031)组织了甲苯水分含量测定的能力验证活动,有18个省、市、自治区共48家实验室参加。介绍了能力验证计划的样品制备、均匀性和稳定性检验以及基于稳健算法A迭代法结果统计和分析等实施过程,对各实验室采用的水分含量测试标准进行了统计和分析,提出了水分含量测定的技术建议。能力验证计划统计结果表明,满意的实验室有43家,占反馈总数的89.6%。     

合成橡胶行业丁苯橡胶门尼黏度数据比对结果分析

参与苯乙烯-丁二烯橡胶生胶门尼黏度数据比对实验室为50家,比对数据均采用稳健统计技术进行了处理和分析评价,Z比分数统计结果表明,45家实验室的测试结果为满意结果,所占比例为90. 0%,3家实验室的测试结果可疑,所占比例为6. 0%,2家实验室的测试结果离群为不满意结果,所占比例为4. 0%。因此,合成橡胶行业苯乙烯-丁二烯橡胶门尼黏度比对满意结果占90%。     

广西土壤中重金属能力验证结果与分析

通过能力验证评价广西实验室土壤中砷、铜、锌、铅、镉、铬、汞、锰、镍等9种重金属的检测能力。本次能力验证分割水平样品设计,采用稳健统计方法对实验室检测能力进行评价。结果表明:共66个实验室参加本次能力验证,结果满意率分别为砷81.8%、铜85.7%、锌82.5%、铅87.9%、镉为89.2%、铬为84.4%、汞78.1%、锰84.3%、镍82.1%。与2013年能力验证比较分析,参加实验室总数提高100%,砷、铅、镉、汞满意率提高0.5%～22.5%。广西实验室已较好的具备土壤重金属的检测能力。     

基于迭代统计的沥青软化点测定的能力验证

介绍了沥青软化点测定能力验证计划的样品制备、均匀性和稳定性检验、以及基于稳健算法A迭代法的结果统计和分析等实施过程,对各实验室采用的软化点测试标准进行了统计和分析,提出了软化点测定的技术建议。能力验证计划统计表明,满意的实验室有95家,占反馈总数的92.2%。     

中国丁二烯橡胶检测水平评价

利用稳健统计技术对中国合成橡胶行业的17家检测实验室所做的丁二烯橡胶检测数据进行了比对分析,对各实验室检测能力进行了评价.结果表明,5个实验室全部数据的稳健统计绝对值小于2,属满意结果;10个实验室分别有1～3项稳健统计绝对值在2和3之间,数据可疑;6个实验室有1～3项稳健统计绝对值不小于3,数据离群.所有参加比对的实验室基本代表了中国合成橡胶行业的丁二烯橡胶测试水平;合成橡胶生产企业的实验室测试水平高于加工企业;通过中国国家实验室认可的实验室的测试水平高于未通过中国国家实验室认可的实验室.     

蒸馏酒中铅和锰的能力验证及分析方法

评价参与实验室能力验证蒸馏酒中铅和锰测定能力。以蒸馏酒为样品,依据ISO 13528:2005和中国合格评定国家认可委员会(CNAS)规定的程序进行本次能力验证。采用Z值分数评价各参加实验室的测试结果。参加蒸馏酒中铅和锰能力验证的17家实验室中,A样品中铅和锰检测有2家结果“不满意”,2家结果“可疑”,B样品中铅和锰检测16家结果“不满意”,1家结果“可疑”。     

Determination of Semivolatile and Particulate Polycyclic Aromatic Hydrocarbons in SRM 1649a and PM 2.5 Samples by HPLC-Fluorescence

The concentrations of 15 "priority pollutant" semivolatile and particulate polycyclic aromatic hydrocarbons (PAHs) were determined in three sets of samples supplied by the National Institute for Standards and Technology (NIST) as part of an interlaboratory analytical exercise. The purpose of the exercise, organized by NIST and the U.S. Environmental Protection Agency, was to determine the comparability of measurements for various organic analytes among the participating laboratories, and to establish consensus values for SRM 1649a and interim materials. The commercially available SRM 1649a Atmospheric Urban Dust and two subsamples of this popular reference material were analyzed: an extract designated as Air Particulate Extract, and a resieved portion labeled Air Particulate I. The method used in our laboratory for the exercise consists of the extraction of the PAHs from the solid samples by ultrasonication, followed by separation and quantification using high-performance liquid chromatographyfluorescence detection. The accuracy and precision of the results obtained by our analytical protocol and by 14 other participating laboratories were evaluated using the International Union of Pure and Applied Chemistry guidelines of z-scores ( = 25% of the exercise assigned value) and p -scores. Using these guidelines the accuracy of our method provided results that are satisfactory for all 15 target PAHs (|z| h 2) determined in the Air Particulate Extract and, except for fluorene, in the Air Particulate I sample. Finally, application of the methodology is demonstrated for the quantification of PAHs present at the pg m m 3 range in PM 2.5 samples collected from 163 m 3 of air in the Los Angeles basin.     

Determination of 3‐MCPD esters in edible oil – methods of analysis and comparability of results

The discovery of fatty acid esters of 3‐chloropropane‐1,2‐diol (3‐MCPD) in edible oil products initiated food monitoring campaigns in many EU Member States. As the determination of 3‐MCPD esters was new to most laboratories, questions on the reliability of the produced analysis data were raised. In response to this, the Institute for Reference Materials and Measurements (IRMM) of the European Commission's Joint Research Centre (JRC) organised a proficiency test on the determination of 3‐chloropropane‐1,2‐diol esters (3‐MCPD esters) in edible oils. The aim of this proficiency test was to scrutinise the capabilities of official food control laboratories, private food control laboratories as well as laboratories from food industry to determine the 3‐MCPD esters content of edible oils. The study was carried out in accordance with “The International Harmonised Protocol for the Proficiency Testing of Analytical Chemistry Laboratories” and ISO Guide 43. The test materials dispatched to the participants were: refined palm oil, extra virgin olive oil spiked with 3‐chloropropane‐1,2‐dioleate and 3‐MCPD standard solution in sodium chloride. Altogether 41 laboratories from 11 EU Member States, Switzerland and Macedonia subscribed for participation in the study. The analysis task was to determine the 3‐MCPD esters content as total 3‐MCPD content of the test samples. Participants were free to choose their analysis methods. In total, 34 laboratories reported results to the organisers of the study. The performance of laboratories in the determination of 3‐MCPD esters in edible oils was expressed by z‐scores. About 56% of the participants performed satisfactorily in the determination of 3‐MCPD esters in palm oil and 85% for the spiked extra virgin olive oil test sample. The study revealed that the direct transesterification of the sample without the prior removal of glycidol esters might lead to strong positive bias.     

Preparation of Test Material and Evaluation of a Proficiency Test for Official Food Control Laboratories on the Determination of Polycyclic Aromatic Hydrocarbons in Baby Food

A proficiency test on the determination of polycyclic aromatic hydrocarbons (PAHs) was organized by the German National Reference Laboratory for PAH in 2010. The test samples were produced by spiking cereal-based instant baby food with PAHs at concentration levels between 0.6 and 3.8 μg/kg; homogeneity and stability of the test material were verified before sample dispatch. Twenty-one official laboratories from Germany and Austria participated in the test and the evaluation of the test was done by applying methods of robust statistics. The individual performance was assessed with the help of z-scores. As to the quantitative results, the dispersion of data for the most important group of benzo(a)pyrene (BaP), benz(a)anthracene (BaA), benzo(b)fluoranthene (BbF), and chrysene (CHR) appeared to be acceptable, with a relative robust standard deviation ranging from 13.2% for BbF to 26.7% for BaA. In total, the performance of one laboratory had to be rated as unsatisfactory because of a result for BaP outside the limits of tolerance. The methods applied in the test may be considered to be comparable, as no significant effects in the distribution of data could be attributed to certain analytical procedures.     

Proficiency test on the determination of mineral oil in sunflower oil

Following the discovery of mineral oil contamination of Ukrainian sunflower oil in April 2008, the Institute for Reference Materials and Measurements (IRMM) of the European Commission's Joint Research Centre (JRC) was requested by the Directorate General Health and Consumers (DG SANCO) to organise a proficiency test on the determination of mineral oil in sunflower oil. The aim of this test was to evaluate the comparability of analysis results gained by laboratories in the EU and the Ukraine. The organisation of the study and the evaluation of the results were done in accordance with “The International Harmonised Protocol for the Proficiency Testing of Analytical Chemistry Laboratories” and ISO Guide 43. Altogether 62 laboratories from 19 EU member states, Switzerland and the Ukraine subscribed for participation in the study. Four test samples at concentration levels between about 100 and 350 mg/kg, comprising contaminated crude sunflower oil, contaminated refined sunflower oil, and spiked sunflower oil, and a solution of mineral oil in n‐heptane were dispatched to the participants. The participants were asked to determine the mineral oil content of the test samples by application of their in‐house analysis methods. In total, 55 sets of results were reported to the organisers of the study. The performance of laboratories was expressed by z‐scores for the oil samples and by relative bias for the mineral oil solution in n‐heptane. The percentage of successful laboratories in the determination of the mineral oil content of sunflower oil was for all sunflower oil test materials about 80%.     

Precision of low trans fatty acid level determination in refined oils. Results of a collaborative capillary gas-liquid chromatography study

The results of a collaborative study by 38 laboratories were analyzed statistically to calculate the precision of a novel capillary gas-liquid chromatography (GLC) method for the determination of low levels of trans fatty acids (TFA) in edible oils. The participants came from 17 countries, mainly European, and were spread evenly between Unilever companies and external laboratories. All participants used the same GLC method, including a temperature optimization step, which is suitable for the determination of a large range of TFA levels in refined oils and fats and for the determination of total saturated fatty acid, cis mono- and cis-cis methylene-interrupted polyunsaturated fatty acid isomers. For TFA levels down to 0.5%, the collaborative study yielded values for R_within that ranged from 0.08 to 0.13% (absolute values) and for R_between from 0.2 to 0.4%, depending on the isomer distribution in a particular edible oil. The proposed GLC method allows reliable TFA analysis at low levels that is suitable for monitoring oil processing practices and intake control.     

Capillary GLC: a robust method to characterise the triglyceride profile of cocoa butter — results of an intercomparison study

The results of a method intercomparison study, in which 13 laboratories applied high‐temperature capillary GLC on fused‐silica columns coated with medium‐polarity stationary phases to determine the triglyceride profile of cocoa butter, are reported. The participants did not apply a uniform GLC procedure based on a standard method, but were requested to use their own methodology. However, certain requirements relating to the separation efficiency and the accuracy, had to be fulfilled. The relative standard deviation of the reproducibility was less than 5% for the major triglyceride components of cocoa butter. The results of the present study indicate that neither the type of capillary column employed nor sample injection techniques or other chromatographic conditions influenced to a measurable degree the agreement of results between the participating laboratories. Therefore, we conclude that high‐temperature capillary GLC is a robust and reliable technique for the characterisation of cocoa butter by determining its triglyceride pattern.     

An international round robin test on isothermal (conduction) calorimetry for measurement of three-day heat of hydration of cement

The results of a round robin test on isothermal (heat conduction) calorimetry are presented. A total of 18 participants using three types of instruments conducted 3-day measurements of the hydration of one rapidly hardening Portland cement and one slag-containing cement. The results confirm that isothermal calorimetry is a suitable method for the determination of heat of hydration. As a part of the study, two laboratories also conducted measurements with the standardized heat of solution method. For the Portland cement, these results were in good agreement with the isothermal measurements, but for the slag-containing cement the results differed, both between the two laboratories and between their results and the result of isothermal calorimetry. However, this method performance study clearly shows that the heat of hydration determination of cement by heat conduction calorimetry is more precise than the traditional heat of solution method described in EN 196-8, if state-of-the-art calorimeters are used.     

Interlaboratory comparison of soybean protein and oil determinations

Iowa State University coordinated an interlaboratory comparison study of Kjeldahl protein and ether oil extraction methods. Blind duplicates of 10 clean, single-variety soybean samples were sent to 30 laboratories grouped in 3 categories of 10 each in public (government and university), commercial and processor facilities. Five of the commercial laboratories were AOCS-certified. Standard deviations among laboratory means across all samples were 3.87 and 1.82 percentage points (dry basis) for protein and oil, respectively (0.48 and 0.27, respectively, for the AOCS-certified laboratories). The average differences between blind duplicates of a sample were 0.71 percentage points for protein and 0.87 percentage points for oil (0.28 and 0.45, respectively, for the certified laboratories). Average standard deviations across laboratories on an individual sample were 2.37 and 1.71 percentage points for protein and oil, respectively (1.87 and 0.99, respectively, for the certified laboratories.     

苯乙烯-丁二烯橡胶门尼粘度比对结果评价

按照GB/T1232.1-2000,组织合成橡胶生产、加工、科研和质检的26家实验室进行了苯乙烯丁二烯橡胶门尼粘度数据比对,利用稳健统计技术对比对结果进行评价。所有参加比对的实验室反映了合成橡胶行业门尼粘度测试水平;国家、行业的质检机构显现了出较高的测试水平,科研开发的实验室测试水平有明显提高;生产、加工企业的实验室能够满足测试要求;参加比对的实验室测试水平总体比以往相比均有不同程度的提高。选择Z值较小且经过实验室认可的实验室作为门尼粘度标准物质研制定值单位。     

Strategy to assess exposure of laboratory personnel to select OSHA-regulated chemicals at Massachusetts Institute of Technology

The purpose of this study was to determine the exposure level of personnel engaged in research activities at Massachusetts Institute of Technology laboratories that utilized the following five chemicals regulated by the Occupational Safety and Health Administration (OSHA): benzene, formaldehyde, chloroform, methylene chloride, and arsenic compounds. We describe the process used to select the laboratories to monitor and present the test results of the exposure assessment. Hazardous waste manifests were used to identify 88 laboratories that used these chemicals of 2200 laboratories. Of the 88 laboratories, we collected detailed information on use on the basis of the quantity of the chemicals disposed and the type of laboratory for 27 laboratories. On the basis of the survey findings, eight laboratories were selected for monitoring because of frequency of use of the chemicals. Both personal and area samples were taken. Standard National Institute of Occupational Safety and Health air sampling and analytical techniques were used. With one exception, the results showed the exposure levels were well below the OSHA permissable exposure levels and recommended American Conference of Governmental Industrial Hygienists (ACGIH) threshold limit values. Therefore, we conclude that for typical laboratory activities, exposure levels should be well below the relevant threshold limit values if engineering controls are working properly and if proper procedures are followed.