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1.
T. Drglin 《Accreditation and quality assurance》2003,8(3-4):130-133
A validation procedure based on the ISO/IEC 17025 standard was used to demonstrate the long-term stability of a calibration
process and to assess the measurement uncertainty of a standard test method for optical emission vacuum spectrometric analysis
of carbon and low-alloy steel (ASTM E 415–99a). The validation was used to provide documented evidence that the selected method
fulfils the requirements and that the method is ”fit for purpose”. A test for drift was applied to determine statistically
whether the analytical results vary systematically with time. The accuracy and traceability of the optimised method were tested
by an analysis of closely matched matrix certified reference materials (CRMs). The measurement uncertainty estimations took
account of the precision study, the bias and its uncertainty, and the qualification of uncertainties not considered in the
overall performance studies.
Received: 2 November 2002 Accepted: 2 January 2003
Acknowledgement The author expresses gratitude to Dr. Aleš Fajgelj for helpful discussions during the 3rd Central European Conference on Reference Materials and Measurements.
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 T. Drglin 相似文献
2.
An analytical result is not considered to be complete without a statement of the measurement uncertainty associated with
it. Evaluation of measurement uncertainty is therefore an essential part of every determination. In the present study the
measurement uncertainty of the result of determination of selenium in the reference material Seronorm Trace Elements Serum
was studied. The combination of a digestion procedure using sulfuric acid, V2O5 in H2SO4 and hydrogen peroxide and the continuous flow approach of hydride generation atomic fluorescence spectrometry (HG-AFS) detection
was used for selenium determination. The total uncertainty budget was calculated with the help of the GUM Workbench program,
in which computations follow the rules of the ’ISO guide to the expression of uncertainty in measurement’. The major sources
of uncertainty were found to be due to the recovery of the procedure, measurement of peak heights and the purity of Na2SeO3. A selenium mass fraction of 77.1±4.8 ng/g (with a coverage factor of 2.1, 95% probability) was determined, which is comparable
with the recommended value of 80 ng/g.
Received: 13 September 2002 Accepted: 23 December 2002
Acknowledgements We would like to thank Tinkara Buˇcar, B.Sc. for useful discussions and the IAEA Vienna, for financial support of the project
11553/RO.
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 V. Stibilj 相似文献
3.
4.
A simple and rapid method is developed to determine the high acidity and the basicity of solutions by chronopotentiometry with a platinum working electrode. The acidity range from 5.0 mol/l H+ to 1.0 mol/l OH− can be measured by the adjustment of deposition potential and time. The response mechanism to acidity and basicity has been explored. The transition potential plateau in chronopotentiograms is caused from the oxidation of hydrogen adsorbed on electrode surface. 相似文献
5.
论测量不确定度 总被引:14,自引:1,他引:14
胡晓燕 《理化检验(化学分册)》2002,38(8):406-409
讨论了测量不确定度的基本概念及应用。分析了误差和不确定度两个概念的区别,探讨了不确定度及分量的评定方法。 相似文献
6.
Reliable, traceable and comparable measurements provide the rational basis for evaluation of the quality of a result and
the starting point for recognized laboratory accreditation in any national area. Modern medical diagnostics and treatment
involve rapidly rising numbers and types of clinical laboratory measurements, that are reliable. Therefore, the basic principles
to be followed to assure the traceability of clinical measurements as required by the Romanian Laws of Metrology are reviewed.
Main sources affecting the quality of the unbroken chain of calibrations that relate the measurements back to appropriate
measurement standards are discussed. Examples of how to achieve traceable measurements in clinical laboratories are presented.
Details of specific uses of reference materials, measuring instruments and standard measurement methods are also discussed.
Received: 8 January 1998 · Accepted: 21 April 1998 相似文献
7.
Vapor pressure data were measured for water, methanol and ethanol as well as their binary mixtures with an ionic liquid (IL) 1-ethyl-3-methylimidazolium dimethylphosphate ([EMIM][DMP]) at varying temperature and IL-content ranging from mass fraction of 0.10–0.70 by a quasi-static method. The vapor pressure data for the IL-containing binary systems were correlated using NRTL equation with average absolute relative deviation (ARD) within 0.0076, and the binary NRTL parameters was used for predicting the vapor pressure of the IL-containing ternary systems with reasonable accuracy. In addition, the infinite activity coefficients of solvents in [EMIM][DMP] and isobaric vapor–liquid equilibrium for IL-containing ternary systems at 101.325 kPa and mass fraction of IL being 0.5 were predicted with the regressed NRTL parameters. The results indicate that ionic liquid [EMIM][DMP] can depress the volatility of the solvents of water, methanol and ethanol but to a varying degree, leading to the variation of relative volatility of a solvent and even removal of azeotrope for water–ethanol mixture. 相似文献
8.
We consider a decentralized LQG measurement scheduling problem in which every measurement is costly, no communication between observers is permitted, and the observers' estimation errors are coupled quadratically. This setup, motivated by considerations from organization theory, models measurement scheduling problems in which cost, bandwidth, or security constraints necessitate that estimates be decentralized, although their errors are coupled. We show that, unlike the centralized case, in the decentralized case the problem of optimizing the time integral of the measurement cost and the quadratic estimation error is fundamentally stochastic, and we characterize the -optimal open-loop schedules as chattering solutions of a deterministic Lagrange optimal control problem. Using a numerical example, we describe also how this deterministic optimal control problem can be solved by nonlinear programming.This research was supported in part by ARPA Grant N00174-91-C-0116 and NSF Grant NCR-92-04419. 相似文献
9.
Standardising quality of measurements at both the national and international level results in a unity in measurement that
may be regarded a synonym of traceability. In gas analysis, the key issue in achieving this aim is production of gaseous reference
materials. Establishing a network of secondary measurement standards at gaseous CRM producers’ sites in Ukraine might be interesting
for those involved in gas analysis activities. Inevitably, problems concerning the recognition of measuring capabilities of
both national metrological institutes and local CRM producers are now an international issue. Thus, the problems of national
adoption of international standards, as well as harmonisation between different international documents are currently relevant,
and Ukrainian experience may be useful to others in this field.
Presented at the 3rd International Conference on Metrology, November 2006, Tel Aviv, Israel. 相似文献
10.
In the EURACHEM/CITAC draft ”Quantifying uncertainty in analytical measurement” estimations of measurement uncertainty in
analytical results for linear calibration are given. In this work these estimations are compared, i.e. the uncertainty deduced
from repeated observations of the sample vs. the uncertainty deduced from the standard residual deviation of the regression.
As a result of this study it is shown that an uncertainty estimation based on repeated observations can give more realistic
values if the condition of variance homogeneity is not correctly fulfilled in the calibration range. The complete calculation
of measurement uncertainty including assessment of trueness is represented by an example concerning the determination of zinc
in sediment samples using ICP-atomic emission spectrometry.
Received: 9 February 2002 Accepted: 17 April 2002 相似文献