碘量法测定水中溶解氧含量测量不确定度的评定

分析碘量法测定水中溶解氧含量测量不确定度的影响因素，对测量不确定度各个分量的评定结果表明，测量重复性的不确定度分量最大，其次是样品溶液的体积、滴定溶液的体积和滴定溶液的浓度等不确定度分量，计算得到水中溶解氧含量测定结果的合成不确定度为0．06mg/L，扩展不确定度为0．12mg/L。     

自动电位滴定仪测定磁性材料1YC8中钴的测量不确定度评定

采用自动电位滴定仪测定磁性材料1YC8中钴含量,建立了测量过程分量的数学模型,分析了测量过程不确定度来源及各不确定度分量对总不确定度的影响,确定了测定结果的置信区间。给出磁性材料1YC8中钴的含量及其置信区间为10.92%±0.07%。     

原子吸收光谱法测定钛合金中铜含量的不确定度评定

根据航空工业部行业标准检验方法[1],结合实验室的日常分析实际情况,对原子吸收光谱法测定钛合金中微量铜含量进行不确定度评定。对测定过程中的标准曲线、样品称量以及使用仪器带来的不确定度进行了分析,并量化每个不确定度分量,并且确定最大不确定度分量为溶液浓度分量,从而合成标准不确定度以及形成该方法扩展不确定度的表达,为质量控制提供有效、可靠、可溯源的测量数据。     

食盐中碘含量的测量不确定度

根据《测量不确定度评定与表示》（JJF 1059-1999）,对食盐中碘含量的测量不确定度进行评定。建立数学模型,对测量不确定度分量进行分析和量化。当食盐中碘含量为45．86mg／kg时,合成标准不确定度为0．21mg／kg,扩展不确定度为0．42mg／kg。食盐中碘含量的测量不确定度主要来源于硫代硫酸钠标准溶液的浓度和滴定消耗的体积。     

石墨炉原子吸收法测定土壤中镉的测量不确定度评定

石墨炉原子吸收法测定土壤中镉的不确定度主要来源于称量样品、定容样品消解液、测定样品消解液中镉的质量浓度及测定土壤水分引入的不确定度。对各不确定度分量进行了计算,求得合成标准不确定度和扩展不确定度分别为0.0026、0.005mg/kg。镉测量不确定度的主要来源是测定样品消解液中镉质量浓度引入的不确定度。     

石墨炉原子吸收光谱法测定土壤中铅量的测量不确定度评定

通过石墨炉原子吸收光谱法对土壤中的铅量进行了测定,对影响测量结果的不确定度分量进行了量化的计算.从而得出影响铅量测量不确定度的主要因素是测量样品消解液中的铅的质量浓度引起的不确定度.     

氢化物发生原子荧光法测定聚氯化铝中砷含量的不确定度评定

依据JJF 1059-1999，对氢化物发生原子荧光法测定聚氯化铝中的砷含量进行不确定度评定。建立了数学模型，对各不确定度分量进行了分析和量化。计算出相对合成标准不确定度为0．0095，扩展不确定度为0．032mg／kg。砷含量测量不确定度主要来源于测量样品测试液中砷浓度产生的不确定度。     

液相色谱仪检测器的最小检测浓度测量结果不确定度的评定

依据JJF1059-1999《测量不确定度评定与表示》,评定了液相色谱仪检测器最小检测浓度测量结果的不确定度。分析了各不确定度分量,建立了评定最小检测浓度不确定度的数学模型。检测器最小检测浓度测量结果的相对扩展不确定度为7.1%(k=2.53)。     

铀矿石中铀测量结果的不确定度评定

分析了容量法测定铀矿石中铀含量测量不确定度的影响因素。对样品质量、滴定样品溶液消耗的钒酸铵溶液的体积、钒酸铵对铀的滴定度等不确定度分量进行了分析和计算。铀矿石中铀含量为0．427％时,测量结果的扩展不确定度为0．020％。     

火焰原子吸收光谱法测定土壤中锌含量的测量不确定度评定

火焰原子吸收光谱法测定土壤中锌含量的不确定度主要来源于测量样品消解液中锌的浓度、测量过程中使用的玻璃量具及样品称量产生的不确定度,对这些分量进行了量化计算,求得合成标准不确定度和扩展不确定度分别为1．29、2．6mg／kg。影响锌含量测量不确定度的主要因素是测量样品消解液中锌的浓度引起的不确定度。     

电感耦合等离子体发射光谱法测定镍钴锰氢氧化物中硫酸根含量的不确定度评定

采用电感耦合等离子体发射光谱法(ICP-OES)测定镍钴锰氢氧化物(三元正极材料NCM前驱体)中硫酸根含量.确定了适宜的测试条件,依据不确定度评定的方法,分析了不确定度来源、量化不确定度分量、计算检测结果的合成标准不确定度和扩展不确定度.结果表明,NCM前驱体中硫酸根的质量分数为2 709±88 mg/kg,样品加标回收率为97.5%～99.7%,相对标准偏差(RSD)为2.02%.方法简单、快速.     

Sorption of 60Co on a synthetic titanosilicate analogue of the mineral penkvilksite-2O and antimonysilicate

The ability of two different types of synthetic inorganic ion-exchangers to sorb radioactive cobalt-60 using a batch-type method was studied. The two materials examined were the analogue of the natural titanosilicate penkvilksite-2O (AM-3) and a synthetic antimonysilicate. Ion-exchange experiments were performed with solutions labelled with radioactive cobalt (⁶⁰Co). The sorption of ⁶⁰Co onto the two samples materials were compared in terms of distribution coefficient (K _d), sorption percentage and cobalt quantity removed in mg per gram weight of the material. Several parameters were investigated viz. contact time, cobalt concentration, and sorbent concentration. It was found that the batch factor and cobalt concentration had a significant influence on the sorption of cobalt onto both of the materials. This was associated with the difference in pH generated by suspensions of the materials in water which was alkaline for the penkvilksite-2O analogue, and acid for the synthetic antimonysilicate.     

Determination of cobalt in solid matrices by neutron activation analysis

The concentration of cobalt in 2 solid matrices was determined by neutron activation analysis (NAA) using standard solutions which were prepared by dissolving pure cobalt in nitric acid. The matrices assayed were a cobalt-aluminium wire and an iron foil and the respective Co concentrations found were 0.488% and 0.138%. Both solid materials can equally be used as standard references of cobalt in NAA. Subcadmium and epicadmium neutron fluxes in the reactor core were determined using Co?Al and Au?Al alloy wires. Very good agreement was obtained for all irradiation configurations of the target monitors cobalt and gold.     

Estimation of exposure levels by measurements and models

Summary Results from environmental and biological monitoring programs are abundant, but it is a question to what extent such data can be used for exposure assessments. The quality of such data depends not only on sampling and analytical errors, but also, and probably more, on the sampling strategy used. Therefore, uncritically use of such results can be biased and associated with large variations. The size of bias between two studies carried out in the same industry was found to be a factor of 5–7. Samples that are not representative of the exposed population studied are misleading. An estimation of exposure to cobalt in the porcelain industry illustrates the distinction between biological measurement data and air cobalt measurement data done on selected individuals. Following improvement of the working environment during the period 1983–1990, the change of cobalt concentration in urine indicates a reduction of cobalt exposure with a factor of 10, but air monitoring data do not verify that figure. Furthermore, results must always be interpreted with caution, when used beyond the purpose for what they were originally made. Great care should be taken to secure that data are representative and a quality assurance-quality control program should be used to ensure data quality.     

Determination of the Uncertainty of the Flame Atomic Absorption Spectrometer for Copper,Cobalt, Cadmium,and Nickel

Abstract

The sources of uncertainty in the determination of copper, cobalt, cadmium, and nickel, originating from the flame atomic absorption spectrometer, were studied. They were identified and divided in three main groups according to their origin—from the flame, from the light source (hollow-cathode lamp), and from the optics. The combined uncertainty of the flame atomic absorption determination was experimentally determined.     

Method for precisely analyzing the stoichiometry of NaxCoO2-type superconductor material

An analytical procedure for precisely determining the stoichiometry of Na_xCoO₂-type superconductor material is presented. Sodium and cobalt contents, ranging between 3.5 and 11 mg L⁻¹ and 18 and 32 mg L⁻¹, respectively, were measured simultaneously using CID–ICP–OES. Sodium was found to significantly lower the emission intensity of cobalt, so the addition of 6.4 g L⁻¹ of the ionization buffer LiCl was required to compensate for this effect. The recoveries and precisions of the measurements were significantly increased by internal standardization using yttrium: Co(II) emission intensities at 230.786 nm, 237.862 nm, and 238.346 nm can be corrected using Y ion emission intensities, as can the atomic emissions of Co at 345.351 nm and Na at 589.592 nm. The cobalt contents of three real superconductor samples were independently verified by complexometric titration using EDTA. The valence state of cobalt was determined with a relative uncertainty of ~0.5% by redox titration using sodium oxalate as reductive agent and Ce(SO₄)₂ solution. The final stoichiometries of the superconductor samples can be calculated using the Na and Co contents, and the Co valence state. Conclusions about the quality of the prepared samples in terms of phase purity and presence of side products are drawn.     

Trace determination of cobalt ion by using malic acid-malonic acid double substrate oscillating chemical system

A novel kinetic method for determination of trace amounts of cobalt ion was proposed and validated. The method is based on adding malic acid into classical Belousov-Zhabotinskii （B-Z） oscillating chemical system to form a double substrate one. The results showed that when the concentration of cobalt ion was in the range of 5.27× 10^-8 to 5.37 × 10^-12 mol L^-1, the change of the oscillating period was directly proportional to the negative logarithm of cobalt ion concentration. The sensitivity and precision of the developed method were quite satisfactory. The limit of detection was down to 5.20 × 10^-13 mol L^-1 which was a highest sensitivity found for determination of metal ions using oscillating chemical reaction so far. Some factors influencing the determination were also examined. The method has been successfully used to determine cobalt ion in vitamin B12 injection.     

Uncertainty budget for final assay of a pharmaceutical product based on RP–HPLC

Compliance with specified limits for the content of active substance in a pharmaceutical drug requires knowledge of the uncertainty of the final assay. The uncertainty of measurement is based on the ISO recommendation as expressed in the Guide to the Expression of Uncertainty in Measurement (GUM). The reported example illustrates the estimation of uncertainty for the final determination of a protein concentration by HPLC using UV detection, using the approach described by EURACHEM/CITAC. The combined standard uncertainty for a protein concentration of 2400 µmol/L was estimated to be 14 µmol/L.. All known and potential uncertainty components are presented in Ishikawa diagrams and were carefully evaluated using Type A or Type B estimates. Special efforts were made to avoid duplication or omission of significant contributions to the combined uncertainty. Hence, before accepting the uncertainty budget, the estimated combined standard uncertainty was verified using the variation observed in a number of quality control samples.     

A sensitive and simple extractive-spectrophotometric method for the determination of microgram amount of cobalt by using alpha-benzilmonoxime.

Alpha-benzilmonoxime has been used for the extraction and determination of cobalt at microgram amount. The reagent reacts with cobalt(II) in the pH range of 8.8 - 9.3 to form a yellow-color chelate, which is extracted in chloroform, toluene, and some other non-polar solvents. The chelate is stable in chloroform for about one day. Under the optimum conditions of the a-benzilmonoxime concentration and pH of 9.0, Beer's law was obeyed in the concentration range of 0.08 - 2.2 microg/ml cobalt. The molar absorptivity of the extracted species was 2.55 x 10(4) dm3/mol cm at 380 nm, with a detection limit of 0.01 microg/ml cobalt. Relative standard deviations of 0.4, 0.8 and 2.3% were found for the determination of cobalt concentrations of 2.2, 1.1 and 0.08 microg/ml, respectively. The effect of diverse ions on the determination of 1.00 microg/ml of cobalt has been studied. The method was applied to the determination of cobalt in vitamin B12 and B-complex ampoules, a Co2O3-Co3O4 laboratory chemical mixture and some synthetic alloy samples. The method is sensitive, simple, rapid and accurate.     

气相色谱-质谱法测定食品接触材料中五氯苯酚含量的不确定度评定

对气相色谱-质谱联用法测定食品接触材料中五氯苯酚含量过程中可能引入的不确定度进行了分析和评定.通过实验数据计算得出食品接触材料中五氯苯酚含量的不确定度,当置信水平为95%,包含因子k=2时,其相对扩展不确定度为4.04%.通过对不确定度的分析.指出在检测过程中质量控制的关键在于标准物质的浓度和气相色谱分析过程,并提出了...