Uncertainty of carboxyhaemoglobin determination in putrefied blood by headspace gas chromatography

The uncertainty of carboxyhaemoglobin (COHb) determination in post-mortem blood samples by headspace gas chromatography with the use of methanizer and flame ionization detector was estimated. Four main components of uncertainty were identified, i.e. calibration, measurement repeatability, standard solutions preparation and sample preparation, and their contributions to the combined uncertainty were determined. The calibration step was the dominating source of uncertainty, counting for more than 39 % of overall variance. The contribution of remaining sources to the combined uncertainty was lower than 31 % (measurement repeatability), 21 % (standards preparation) and 12 % (sample preparation). The calculated absolute expanded uncertainty in samples containing 3.8–82 % mass fraction of COHb ranged between 2.2 % and 2.6 % (coverage factor 2), depending only slightly on the analyte level in the analysed sample.     

不锈钢1Cr18Ni9Ti中铬含量测量不确定度的评定

采用国际通用的方法研究了过硫酸铵氧化容量法测定铬含量的不确定度,分析了容量法中摩尔质量、样品质量、溶液的体积、温度等因素对测量不确定度的影响,评估了各参数的标准不确定度、合成标准不确定度和扩展不确定度。找出了影响容量法测定铬含量准确度的主要原因。     

电感耦合等离子体质谱法测定酱油中铅和总砷含量的不确定度评定

根据实验过程的数学模型,分析了电感耦合等离子体质谱法测定酱油中铅和总砷含量的不确定度来源,对不确定度分量进行计算,并计算出合成不确定度及扩展不确定度。     

气相色谱-质谱联用法测定化妆品中邻苯二甲酸酯类化合物的不确定度评定

气相色谱-质谱联用法测定化妆品中邻苯二甲酸酯类化合物不确定度的主要来源有标准溶液引入的不确定度、样品引入的不确定度、样品处理过程中引入的不确定度。以邻苯二甲酸二丁酯(DBP)为例,对各不确定度分量进行了评定,计算了合成不确定度和扩展不确定度。当化妆品中DBP测量结果为10.39 mg/L时,其扩展不确定度为0.50 mg/L(k=2)。     

Determination of measurement uncertainty for the determination of triazines in groundwater from validation data

Laboratories are increasingly urged to submit full uncertainties of their analytical results rather than only standard deviations. The determination of measurement uncertainties in compliance with the Guide to the Expression of Uncertainty in Measurement (GUM) is demonstrated using the validation approach explicitly endorsed by the recent edition of the EURACHEM guide for the determination of measurement uncertainty. Measurement uncertainty was split into uncertainty of the sample mass, uncertainty of the concentration of the stock standard solution, uncertainty of the calibration and uncertainty connected to within- and between-series precision. Uncertainties of sample mass and of the concentration of the stock standard solution were 0.26 and 1.14% for all analytes, which is negligible compared with the contributions of precision and calibration. Uncertainty of calibration was estimated from the calibration graph. Relative uncertainty of calibration was found to be strongly concentration dependent and to be the main uncertainty contribution below 0.2 microgram L-1. Precision was split into within-series and between-series standard deviation, which dominate the combined standard uncertainty at higher concentrations. The results obtained from these calculations are compared with results for a certified reference material and with the performance in an interlaboratory comparison. It was found that all results agreed within their uncertainty with the target values, showing that the estimated uncertainties are realistic.     

Exhaled breath condensate as a biomonitor for metal exposure: a new analytical challenge

The study of exhaled breath condensate (EBC) obtained by cooling exhaled air under conditions of spontaneous breathing is considered one of the areas with higher interest in respiratory health research. The use of EBC for elemental determination in occupational exposure requires a standard methodological procedure to implement its practice in occupational studies. EBC is an inhomogeneous sample with organic and particulate matter in suspension, which may hamper analytical results reliability. Total reflection X-ray fluorescence and inductive coupled-plasma mass spectrometry (ICP-MS) techniques were chosen as both are multielemental, require small sample volumes and have appropriate detection limits. Estimation of the overall uncertainty in both techniques was carried out using a pool of EBC collected from a group of workers of a lead processing industry to perform precision and trueness studies for K, Mn, Cu, Cd, Sb and Pb. Precision was estimated in terms of repeatability using the native EBC sample pool and trueness in terms of recovery obtained from spiking aliquots of the EBC pool with K, Mn, Cu, Cd, Sb and Pb at different concentrations. Recovery was the most significant contribution to total uncertainty. The overall uncertainties obtained for ICP-MS enabled to discriminate between groups of individuals exposed to different levels of contaminants. Therefore EBC proved to be useful in human biomonitoring.     

硫氰酸盐光度法测定低合金钢中钼的测量不确定度评定

用硫氰酸盐分光光度法测定低合金钢中钼的含量,对测定过程中的不确定分量进行了分析和评定.测量不确定度主要来源于试料称量、标准溶液、校准曲线拟合、玻璃仪器的使用及测量重复性.当钼的含量为0.181%时,其扩展不确定度为0.0064%(k=2).     

分光光度法测定空气中甲醛不确定度评定

采用分光光度法测定空气中甲醛,对测定结果的不确定度进行评定。采用酚试剂分光光度法测定空气中甲醛,分析测定过程中的各项不确定度来源,包括样品采集、标准工作溶液配制、标准工作曲线拟合、测定仪器以及重复测定等引入的不确定度,计算合成不确定度,最后获得相对扩展不确定度。当空气中甲醛质量浓度为0.0244~0.2218 mg/m^3时,测定结果在95%置信区间时的相对扩展不确定度为0.1172(k=2)。不确定度主要来源于A类不确定度和系列标准工作溶液制备、标准工作曲线拟合、水中甲醛溶液标准物质的稀释引入的不确定度。     

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.     

元素分析仪测定土壤氮、碳含量的不确定度评定

用实例对元素分析仪测定土壤氮、碳含量不确定度进行评定.分析讨论了测定过程中不确定度的来源、不确定度分量的计算.结果表明,影响土壤碳、氮含量测定不确定度的主要因素是标准物质的引入和标准曲线的绘制.     

原子吸收光谱法测定载金碳中金含量的不确定度评定

介绍了原子吸收光谱法(AAS)测定载金碳中金含量的不确定度评定方法。建立了不确定度评定的数学模型,对不确定度来源进行分析,并对不确定度分量进行量化。测量不确定度的主要来源为测量重复性引入的标准不确定度、样品称量引入的标准不确定度、样品溶液中金含量测定值的标准不确定度、样品溶解后定容体积的不确定度,其中测量重复性引入的标准不确定度和样品溶液中金含量测定值引入的标准不确定度为不确定度主要来源。当载金碳中金含量为0.56 g/kg时,其扩展不确定度为0.02 g/kg(k=2)。     

茶叶中敌敌畏残留量检测的不确定度评定

依据SN/T 1950-2007方法,对茶叶中敌敌畏残留量的测量不确定度进行分析和评定.该检测过程所产生的测量不确定度主要来源于测量重复性、标准物质纯度、标准物质称量、标准溶液稀释、样品称量、定容体积、标样溶液峰面积和样品溶液峰面积的测量.分析结果表明:茶叶中敌敌畏残留量为0.050 mg/kg时,其扩展不确定度为0....     

Uncertainty estimation of anions and cations measured by ion chromatography in fine urban ambient particles (PM2.5)

The present work presents a measurement uncertainty evaluation according to Guide to the Expression of Uncertainty in Measurement (GUM) of the concentration of the cations K⁺ and Li⁺ and anions NO₃⁻² and SO₄⁻² in fine airborne particulate matter, refers to particles less than 2.5 μm in diameter (PM_2.5), as measured by ion chromatography (US-EPA 300 method). The GUM method is not typically used to report uncertainty. In general, the analytical results only report the measurement’s standard deviation under repetition as an uncertainty; thus, not all sources of uncertainty are considered. In this work, the major sources of uncertainty regarding the measurements were identified as contributions to linear least square regression lines, repeatability, precision, and trueness. The expanded uncertainty was approximately 20% for anions and cations. The largest contribution to uncertainty was found to be repeatability.     

ICP-AES法测定塑料中镉含量的不确定度评定

介绍了用ICP-AES法测定塑料中镉含量的不确定度的评定方法.分析了测量不确定度的主要来源,对测试不重复性、工作曲线非线性、标准溶液、样品质量、定容体积等5个不确定度分量进行分析计算,最后合成ICP-AES法测定塑料中镉含量的相对标准不确定度为1.709%,并计算求得扩展不确定度.     

原子吸收光谱法测定血清中Na+含量不确定度的评定

对测量血清中Na+含量的不确定度进行评定。不确定度的来源主要包括血清样品的消化、制备、定容,Na+标准工作液的配制过程、标准曲线拟合等引入的不确定度,计算出各分量的不确定度,通过合成得到测量结果的合成不确定度、扩展不确定度及测试结果的报告形式。     

ICP-AES法测定土壤中重金属的不确定度评定

摘要对ICP-AES法测定土壤中重金属的不确定度进行评估。以测定土壤中的铜为例,分析了测量不确定度的主要来源,对称样量、定容体积、标准曲线、仪器输出数据的不重复性4个不确定分量进行分析计算,最后合成ICP-AES法测定土壤中重金属的标准不确定度,并计算求得扩展不确定度。     

气相色谱法测定人体血液中乙醇含量的测量不确定度评定

对气相色谱法测定人体血液中乙醇含量的测量不确定度进行评定。人体血液中乙醇含量测量结果的测量不确定度主要来源于相对定量校正因子、检材量、检材中添加内标物叔丁醇的体积、检材中乙醇峰面积的平均值与添加内标物叔丁醇峰面积的平均值之比、无水乙醇的纯度及密度等参数引起的不确定度。当检材中乙醇的含量为0．915mg／mL时,扩展不确定度为O．030mg/mL(k=2)。     

Soil sampling uncertainty on arable fields estimated from reference sampling and a collaborative trial

On three fields of arable land of (3–6)×10⁴ m², simple reference sampling was performed by taking up to 195 soil increments from each field applying a systematic sampling strategy. From the analytical data reference values for 15 elements were established, which should represent the average analyte mass fraction of the areas. A “point selection standard deviation” was estimated, from which a prediction of the sampling uncertainty was calculated for the application of a standard sampling protocol (X-path across the field, totally 20 increments for a composite sample). Predicted mass fractions and associated uncertainties are compared with the results of a collaborative trial of 18 experienced samplers, who had applied the standard sampling protocol on these fields. In some cases, bias between reference and collaborative values is found. Most of these biases can be explained by analyte heterogeneity across the area, in particular on one field, which was found to be highly heterogeneous for most nutrient elements. The sampling uncertainties estimated from the reference sampling were often somewhat smaller compared to those from the collaborative trial. It is suspected that the influence of sample preparation and the variation due to sampler were responsible for these differences. For the applied sampling protocol, the uncertainty contribution from sampling generally is in the same range as the uncertainty contribution from analysis. From these findings, some conclusions were drawn, especially about the consequences for a sampling protocol, if in routine sampling a demanded “certainty of trueness” for the measurement result should be met.     

电感耦合等离子体质谱法测定食用植物油中铅、总砷含量不确定度评定

采用电感耦合等离子体质谱法(ICP-MS)测定食用植物油中铅(Pb)、总砷(As)含量,对测定结果的不确定度进行评定。利用ICP-MS,采用标准加入法测定食用植物油中Pb,As含量,分析测定过程中不确定度来源,包括样品称量、定容、前处理、溶液中Pb和As浓度、重复性测量等引入的不确定度,计算合成不确定度。结果表明,Pb含量为(0.0228±0.013) mg/kg,k=2;As含量为(0.00785±0.0045) mg/kg,k=2。该方法的不确定度主要来源于样品溶液中的Pb,As浓度,评定得到的不确定度可为正确评价测定结果提供科学依据。