ICP-AES测定糖果中铅质量分数的不确定度评定

建立了电感耦合等离子体发射光谱(ICP-AES)测定糖果中铅的相应数学模型, 对数学模型中各个参数进行不确定度来源分析, 分别对A类不确定度或B类不确定度进行评定. 对各不确定度分量合成和扩展, 得到铅质量分数的不确定度. 结果表明: 标准溶液的配制、标准曲线拟合线性方程及样品溶液的定容是不确定度的主要来源.     

电感耦合等离子体原子发射光谱法测定燃料油加氢精制催化剂中铂含量的不确定度评定

评定电感耦合等离子体原子发射光谱法测定燃料油加氢精制催化剂中贵金属铂含量的测量不确定度。电感耦合等离子体原子发射光谱法测量不确定度主要来源于测量重复性、标准工作曲线拟合、天平称量以及标准溶液配制和稀释4个分量,其中测量重复性和标准工作曲线拟合对合成不确定度的贡献最大。结果表明,当燃料油加氢精制催化剂中贵金属铂含量为0.168%时,扩展不确定度为0.006%(k=2)。     

电感耦合等离子体光谱法测定土壤中镍的不确定度评定

建立电感耦合等离子体光谱法测定土壤中镍含量的不确定度评定方法。根据JJF 1135—2005《化学分析测量不确定度评定》和JJF 1059.1—2012《测量不确定度评定与表示》中的有关规定，分析了不确定度的来源，量化了各不确定度分量，计算得到了合成不确定度和扩展不确定度。采用置信概率为95%，包含因子k=2，电感耦合等离子体光谱法测定土壤样品中镍的质量分数测定结果为（35.3±1.2） mg/kg。影响结果不确定度的主要因素为校准曲线拟合、标准溶液配制、样品处理及测量重复性等。     

湿法消解–电感耦合等离子体质谱法测定大米中镉的不确定度评定

建立湿法消解–电感耦合等离子体质谱法测定大米中镉含量的不确定度评定方法.分别对样品称量、消解、定容体积、标准溶液的配制、校准曲线拟合、仪器测量重复性等影响不确定度的分量进行分析,并建立数学模型,系统分析和量化各不确定度分量,按照《测量不确定度评定与表示》(JJF 1059.1–2012)的规定进行合成.结果表明,电感耦...     

ICP-MS法测定玩具材料中可迁移锡含量的不确定度评定

采用电感耦合等离子体质谱(ICP-MS)对玩具材料中的锡含量进行测定,讨论了不确定度的主要来源,从样品称量质量、定容体积及测定用样品溶液中锡含量等方面对不确定度分量进行了评定,最后计算了检测结果的合成标准不确定度和扩展不确定度。     

ICP-MS法测定玩具材料中可迁移锡含量不确定度评定

采用电感耦合等离子体质谱（ICP-MS）对玩具材料中的锡含量进行测定,并且讨论了不确定度的主要来源,从样品称量质量、定容体积及测定用样品溶液中锡含量等方面对不确定度分量进行了评定,最后计算了检测结果的合成标准不确定度和扩展不确定度。     

ICP-AES测定土壤勘查地球化学样品中钼的不确定度评定

采用电感耦合等离子体发射光谱法对土壤勘查地球化学样品中的钼进行测定,并对测量结果进行不确定度评定. 分析了影响测量不确定度的主要来源,对测定全过程的重复性、样品称量、拟合曲线、标准溶液、玻璃量具及仪器等影响不确定度的因素进行分析,按JJF l059—1999《测量不确定度评定与表示》的规定进行评定,并计算出扩展不确定度,使结果的表达更加客观和真实.     

电感耦合等离子体发射光谱法测定锂离子电池石墨负极材料中铁不确定度评定

采用电感耦合等离子体发射光谱法测定锂离子电池石墨类负极材料中铁含量,对测定结果的不确定度进行评定。根据JJF 1059.1—2012《测量不确定度评定与表示》和测定过程中的风险因素,建立数学模型和因果图,分析不确定度来源,计算合成标准不确定度和扩展不确定度。结果表明,测量重复性、标准曲线拟合、提取回收率对测定结果影响较大。当样品中铁含量为495.00 mg/kg时,其扩展不确定度为U=29.89 mg/kg,k=2。     

电感耦合等离子体原子发射光谱法测定塑胶中镉、铅、汞、铬含量的不确定度

对电感耦合等离子体发射光谱法测定塑胶中镉、铅、汞、铬含量的不确定度进行了评定.分析了测定过程中不确定度的主要来源,对各不确定度分量进行了量化.镉、铅、汞、铬的合成标准不确定度分别为0.146、2.27、1.71、1.06 mg/kg.     

电感耦合等离子体-原子发射光谱法测定铅笔表面涂层中钡含量的不确定度

采用电感耦合等离子体-原子发射光谱法(ICP-AES)测定了铅笔杆表面涂层中的钡元素含量;讨论了测量不确定度的主要来源,从样品称量质量、定容体积及测定用样品溶液中钡含量等方面对不确定度分量进行了评定,最后计算了检测结果的合成标准不确定度和扩展不确定度.     

Traceability system for elemental analysis

A complete metrological traceability system for measurement results of chemical analysis was set up. Core components are pure substances (national standards) characterised at the highest metrological level, primary solutions prepared from these pure substances and secondary solutions deduced from the primary solutions and intended for sale. The relative uncertainty of the element mass fraction of the primary substances and solutions is < 0.01 and < 0.05%, respectively. For the certification of transfer solutions and for stability testing, a precision measurement method for element contents has been developed by means of optical emission spectrometry (ICP OES) by which uncertainties between 0.1 and 0.05% can be achieved. The dissemination to field laboratories is effected with the aid of a calibration laboratory of the German Calibration Service (DKD) which certifies the element content of the secondary solutions with an uncertainty ≤ 0.3%. Calibration with these solutions enables the user to establish traceability of his measurement results to the International System of Units (SI). Currently, the system comprises Cu, Fe, Bi, Ga, Si, Na, K, Sn, W, and Pb.     

直读光谱法测量镁合金中锰含量的测量不确定度评定

根据GB/T13748.21-2009镁及镁合金化学分析方法(光电直读发射光谱分析方法测定元素含量)对镁合金中锰元素含量进行了分析,对锰含量测量的不确定度来源进行了分析,并对测量过程中产生的不确定度进行了评定.此外,指出了该方法影响锰元素测量不确定度的主要原因,以期为镁合金中锰元素含量的光谱分析提供参考.     

同位素稀释电感耦合等离子体质谱(ID-ICP-MS)测定植物与人发标准物质中的铅

建立了同位素稀释电感耦合等离子体质谱(ID-ICP-MS)测定铅的方法.考察和讨论了仪器参数对同位素比值测定的影响,优化了仪器的数据采样参数.利用内标Tl对质量歧视、系统漂移进行了校正.讨论了同位素浓缩剂加入量对最终浓度测定值的不确定度的影响.将该方法应用于植物标准物质和人发标准物质的测定,结果令人满意.     

Uncertainty evaluation in the analysis of biological samples by sector field inductively coupled plasma mass spectrometry. Part A: measurements of Be,Cd, Hg,Ir, Pb,Pd, Pt,Rh, Sb,U, Tl and W in human serum

A protocol that utilises data (trueness/recovery, precision and robustness) from validation tests to calculate measurement uncertainty was described and applied to a sector field inductively coupled plasma mass spectrometry (SF‐ICP‐MS)‐based method for the determination of Be, Cd, Hg, Ir, Pb, Pd, Pt, Rh, Sb, U, Tl and W in human serum. The method was validated according to criteria issued by international bodies such as AOAC, Eurachem and ISO and the uncertainty in the analytical measurements was estimated following the Eurachem/Citac guide. The methodology was based on dilution of human serum with water and analysis by serum‐matched standard calibration. The method quantification limits ranged 0.02 µg/L (Tl, Ir) to 0.26 µg/L (Hg). The coefficients of regression were greater than 0.9991 over a range of two orders of magnitude of concentration. The mean trueness was 101% and the mean recovery on three levels of fortification (1‐, 1.5‐, and 2‐times the baseline serum level) ranged between 93.3% and 106%. The maximum relative standard deviation values for repeatability and within‐laboratory reproducibility were 12.8% and 13.5%. The method was robust to slight variations of some critical factors relevant to the sample preparation and SF‐ICP‐MS instrumentation. The relative expanded uncertainty over three levels of concentration ranged from 11.6% (Hg) to 27.6% (Pt), and the uncertainty on the within‐laboratory reproducibility, which included factors such as time, analyst and calibration, represented the main contribution to the overall uncertainty. Copyright © 2010 John Wiley & Sons, Ltd.     

ICP-AES法测定油漆涂层中总铅含量的不确定度评定

根据EURACHEM/C ITAC 2000中的规定评定了ICP-AES法测定油漆中总铅含量的不确定度。结果表明,标准曲线拟合线性方程、标准工作液配制过程、样品重复性分析及消化过程中消化回收率是不确定度的主要来源。油漆涂层中的可溶性铅的检测结果可表示为:(162.7±19.0)mg/kg(k=2)。     

原子吸收法测定蔬菜罐头中铜含量的测量不确定度评定

对GB／T 5009．13－1996《食品中铜的测定方法》中火争原子吸收法测定蔬菜罐头中铜含量的测量不确定度进行评定，根据JJF1059－1999《测量不确定度评定与表示》技术规范的要求，分析了该测量过程的测量不确定度来源，建立了数学模型，并利用标准样品对测量不确定度的各个分量进行计算，计算得该测定水平下铜含量测定结果的扩展不确定度为0．2mg/kg.     

Assessment of the determination of heavy metals in organic soil improvers by ICP–OES

Directive 86/278/EEC sets maximum levels of heavy metals in sewage sludge used in agriculture to regulate the risk of using these organic soil improvers. The assessment of the compliance of soil improvers with this legislation should be supported on measurements with adequately low uncertainty. This work presents a strategy for assessing the performance of the determination of aqua regia extractable Cu, Zn and Cr in organic soil improvers and urban sewage sludges following EN 13650 standard. The measurement procedure validation involves checking the adequacy of the linear weighted regression model for ICP–OES calibration, the determination of the limit of quantification, the assessment of measurement repeatability, intermediate precision and trueness, and the evaluation of the measurement uncertainty using the differential approach. Routine tests quality control, including the estimated measurement uncertainty, is checked through the analysis of control standards, equivalent to calibrators, and reference materials from proficiency tests. Since the estimated relative expanded uncertainty is smaller than the defined target value (40 %), measurements are fit for assessing compliance of the mass fraction of heavy metals in organic soil improvers with the council directive.     

Is the estimation of measurement uncertainty a viable alternative to validation?

Two examples of the use of measurement uncertainty in a development environment are presented and compared to the use of validation. It is concluded that measurement uncertainty is a good alternative to validation for chemical processes in the development stage. Some advantages of measurement uncertainty are described. The major advantages are that the estimations of measurement uncertainty are very efficient, and can be performed before analysis of the samples. The results of measurement uncertainty influence the type of analysis employed in the development process, and the measurement design can be adjusted to the need of the process.     

Uncertainty estimation to evaluate mass balances on a combustion system

Mass balances of ash and potassium for a fluidized bed combustor were performed incorporating measurement uncertainties. The total output mass of ash or a chemical element should be equal to the mass in the input fuel; however, this is not often achieved. A realistic estimation of recovery uncertainty can support the reliability of a mass balance. Estimation of uncertainty helps to establish a reliable evaluation of the recovery ratio of ash mass and elemental mass. This may clarify whether any apparent lack in closing the mass balance can be attributed to uncertainties. The evaluation of measurement uncertainty for different matrices, namely coal, biomass, sand and ashes from different streams was based on internal quality control data and external quality control data, namely analysis of samples from proficiency tests or use of a certified reference material. The evaluation of intermediate precision and trueness allowed the estimation of measurement uncertainty. Due to the different physic and chemical characteristics of the studied matrices, the uncertainty of precision was evaluated using R-charts of data obtained from the analysis of duplicates for the majority of samples. This allowed evaluating sample heterogeneity effects. The instrumental acceptance criterion was also considered and included in the combined uncertainty. The trueness was evaluated using data from several proficiency tests and from analysis of a certified reference material or sample spiking. Statistically significant bias was included.     

Uncertainty of chemical oxygen demand determination in wastewater samples

 The measurement uncertainty of the result of chemical oxygen demand determination in wastewater was evaluated. The major sources of uncertainty of the result of measurement were identified as the purity of reagents, volumetric operations, gravimetric operations, bias, and the repeatability of the method. Identification and evaluation of uncertainty sources was followed by combined uncertainty calculations. The combined uncertainty was compared to the experimentally determined variation and good agreement was found, indicating that the major uncertainty sources had been identified. The results show that the major sources of uncertainty arose from repeatability at high concentration level and volumetric steps at low concentration level, thus revealing the target operations for reducing the measurement uncertainty of this determination. Received: 5 August 2002 Accepted: 5 November 2002 Acknowledgements This research was supported by the Ministry of Education, Science and Sport of the Republic of Slovenia (Project Z2–3530). Presented at CERMM-3, Central European Reference Materials and Measurements Conference: The function of reference materials in the measurement process, May 30–June 1, 2002, Rogaška Slatina, Slovenia Correspondence to A. Drolc