共查询到19条相似文献,搜索用时 109 毫秒
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红外吸收法测定碳含量的测量不确定度评定 总被引:1,自引:0,他引:1
对CCS-140型高频感应炉燃烧红外吸收法测定碳含量的不确定度进行了评定,分析了测量不确定度的主要来源,包括仪器的精密度引入的不确定度,标准物质标准值的不确定度,试样称量的不确定度,以及坩埚、助熔剂等引起的空白不确定度。当碳含量为0.366%时,测量结果的扩展不确定度为0.010%。 相似文献
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研制特征量值为1 000μg/mL甲醇中丙烯酸乙酯溶液标准物质。分别利用气相色谱-质谱联用法、核磁共振波谱法和红外光谱法对丙烯酸乙酯标准品原料进行定性确认。采用质量平衡法对主成分含量进行量值核验,丙烯酸乙酯标准品纯度(质量分数)为99.842%,扩展不确定度为0.3%,量值在证书给出的不确定度范围内,因此采用证书标识量值作为原料标准值,证书中标识的不确定度作为原料不确定度。以丙烯酸乙酯标准品为原料,采用重量-容量法制备溶液标准物质,分别采用F检验和t检验对标准物质进行均匀性和稳定性检验,并对其定值结果的不确定度进行评定。结果表明,该标准物质均匀性和稳定性良好,有效期为12月,定值结果的相对扩展不确定度为2%(k=2),可用于环境样品中丙烯酸乙酯分析方法的确认和评价以及仪器校准与检测质量控制。 相似文献
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以二氧化硫纯度标准物质和高纯氮气为原料,采用与一级标准物质比较法制备了摩尔分数为10~100μmol/mol的氮中二氧化硫标准物质。用二氧化硫分析仪对配制的标准物质进行了机械混匀试验、压力均匀性和时间稳定性试验。结果表明,滚动30~80 min后该标准物质机械混匀良好;经F检验,在10~0.5 MPa范围内该标准物质量随压力变化无显著差异,具有较好的压力均匀性;在–20℃和40℃条件下保存7 d,其量值无显著变化,可满足运输环节量值稳定性要求;在常温下贮存11个月,量值无显著性变化,满足国家二级标准物质稳定性要求。采用与一级标准物质比较法定值,并对定值结果的不确定度进行了评定。研制的低浓度氮中二氧化硫气体标准物质的标准值分别为9.89,55.4,101.2μmol/mol(U_(rel)=2%,k=2),该标准物质满足国家二级标准物质的相关技术要求,可用于仪器校准、测量过程质量控制及分析方法的确认和评价。 相似文献
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为解决检定变压器油中溶解气体分析专用气相色谱仪时遇到样品进样量计算不准,检测器对甲烷气体标准物质无响应,专用软件分析方法不能更改等问题,建立变压器油中溶解气体分析专用气相色谱仪的检定与校准方法。当进样模式为一次进样双柱分流时,按分流比计算分流到检测器的样品体积,其它进样模式按进样体积计算进样量;因色谱软件禁止积分导致CH_4在热导检测器上无响应时,应采用有证标准物质中的H_2或O_2进行检定与校准。以7890B型专用气相色谱仪为例,详细说明了变压器油中溶解气体分析专用气相色谱仪的检定与校准流程。该法为检定人员检定该类专用仪器时提供了参考。 相似文献
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Since the uncertainty of each link in the traceability chain (measuring analytical instrument, reference material or other
measurement standard) changes over the course of time, the chain lifetime is limited. The lifetime in chemical analysis is
dependent on the calibration intervals of the measuring equipment and the shelf-life of the certified reference materials
(CRMs) used for the calibration of the equipment. It is shown that the ordinary least squares technique, used for treatment
of the calibration data, is correct only when uncertainties in the certified values of the measurement standards or CRMs are
negligible. If these uncertainties increase (for example, close to the end of the calibration interval or shelf-life), they
are able to influence significantly the calibration and measurement results. In such cases regression analysis of the calibration
data should take into account that not only the response values are subjects to errors, but also the certified values. As
an end-point criterion of the traceability chain destruction, the requirement that the uncertainty of a measurement standard
should be a source of less then one-third of the uncertainty in the measurement result is applicable. An example from analytical
practice based on the data of interlaboratory comparisons of ethanol determination in beer is discussed.
Received: 5 October 2000 Accepted: 3 December 2000 相似文献
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W. Schrön A. Detcheva B. Dreßler K. Danzer 《Analytical and bioanalytical chemistry》1998,361(2):106-109
Direct solid sampling graphite furnace AAS (SS-GF-AAS) provides an advantageous alternative to the conventional AAS which
requires wet digestion of the samples. This method is suitable for trace element determination in calcium fluoride and other
fluoride-containing samples. Matrix effects were studied by using calibration standards, certified reference materials with
different matrices and by means of three-dimensional calibration. 3D calibration is suitable for selection of calibration
samples for more reliable analyses. Cu, Pb, Cd, Zn, and Fe were determined by means of calibration with variation of sample
weight using certified reference materials and suitable fluoride-containing calibration samples.
Received: 25 July 1997 / Revised: 15 December 1997 / Accepted: 20 December 1997 相似文献
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W. Schr?n A. Detcheva B. Dre?ler K. Danzer 《Fresenius' Journal of Analytical Chemistry》1998,361(2):106-109
Direct solid sampling graphite furnace AAS (SS-GF-AAS) provides an advantageous alternative to the conventional AAS which
requires wet digestion of the samples. This method is suitable for trace element determination in calcium fluoride and other
fluoride-containing samples. Matrix effects were studied by using calibration standards, certified reference materials with
different matrices and by means of three-dimensional calibration. 3D calibration is suitable for selection of calibration
samples for more reliable analyses. Cu, Pb, Cd, Zn, and Fe were determined by means of calibration with variation of sample
weight using certified reference materials and suitable fluoride-containing calibration samples.
Received: 25 July 1997 / Revised: 15 December 1997 / Accepted: 20 December 1997 相似文献
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Maria Bertília Oss Giacomelli Maria Carminati Lima Volnei Stupp Rui Miguel de Carvalho Júnior Jos Bento Borba da Silva Pilar Bermejo Barrera 《Spectrochimica Acta Part B: Atomic Spectroscopy》2002,57(12):2151-2157
In this work, tetramethylammonium hydroxide (TMAH) was used to solubilize the DORM-1 dogfish muscle certified reference material as a model substance for the determination of As, Cd, Pb and Se by electrothermal atomic absorption spectrometry (ET AAS). The sample was mixed with a small amount of TMAH and heated to 60 °C for 10 min in a water bath. After dissolution, As and Se were determined using palladium and magnesium nitrates as a chemical modifier added in solution. For Cd and Pb, best results were obtained with a mixture of 250 μg of each of iridium and rhodium as permanent modifiers. In both cases, the calibration was performed with aqueous solutions in 0.2% v/v HNO3. The temperature program for each analyte was optimized using pyrolysis and atomization curves established with the fish reference material. The detection limits in dry samples and the characteristic mass values were: Cd 0.005 μg g−1 and 0.9 pg; Pb 0.04 μg g−1 and 7.6 pg; As 0.4 μg g−1 and 13 pg and Se 0.6 μg g−1 and 20 pg, respectively. Results from the determination of these elements in the DORM-1 certified fish reference material were within the 95% confidence interval of the certified values. 相似文献
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以高纯丙烯腈和高纯氮气为原料,采用称量法配制氮中丙烯腈气体标准物质。对配制的气体标准物质分别进行机械混匀试验、压力均匀性和时间稳定性试验。经F检验,2.00μmol/mol及5.00μmol/mol两种浓度的样品在0.5~10 MPa范围内标准值无显著变化,具有较好的压力均匀性;在–20℃和40℃条件下保存7 d,其量值无显著变化,可满足运输环节量值稳定;在常温下贮存9个月量值无显著变化,表明其稳定性良好,满足国家二级标准物质对有效期的要求。对定值结果的不确定度进行评定。配制的氮中丙烯腈气体标准物质标准值为(2~5)×10~(–6)mol/mol,相对扩展不确定度为9%(k=2)。该标准物质达到国家二级标准物质的相关技术要求,可用于对丙烯腈气体报警器的校准。 相似文献