共查询到20条相似文献,搜索用时 15 毫秒
1.
V. J. Barwick S. L. R. Ellison M. J. Q. Rafferty R. S. Gill 《Accreditation and quality assurance》2000,5(3):104-113
A protocol has been developed illustrating the link between validation experiments and measurement uncertainty evaluation.
The application of the protocol is illustrated with reference to a method for the determination of three markers (CI solvent
red 24, quinizarin and CI solvent yellow 124) in fuel oil samples. The method requires the extraction of the markers from
the sample matrix by solid phase extraction followed by quantification by high performance liquid chromatography (HPLC) with
diode array detection. The uncertainties for the determination of the markers were evaluated using data from precision and
trueness studies using representative sample matrices spiked at a range of concentrations, and from ruggedness studies of
the extraction and HPLC stages.
Received: 10 April 1999 · Accepted: 24 September 1999 相似文献
2.
A protocol has been developed illustrating the link between validation experiments, such as precision, trueness and ruggedness
testing, and measurement uncertainty evaluation. By planning validation experiments with uncertainty estimation in mind, uncertainty
budgets can be obtained from validation data with little additional effort. The main stages in the uncertainty estimation
process are described, and the use of trueness and ruggedness studies is discussed in detail. The practical application of
the protocol will be illustrated in Part 2, with reference to a method for the determination of three markers (CI solvent
red 24, quinizarin and CI solvent yellow 124) in fuel oil samples.
Received: 10 April 1999 / Accepted: 24 September 1999 相似文献
3.
In the present paper, a methodology for method validation and measurement uncertainty evaluation for the measurement of mass concentration of organic acids in fermentation broths was developed. Acetic acid was selected as a representative of organic acids. A detailed procedure for in-house method validation based on simple experimental design and consistent statistics is presented. In addition, a step-by-step illustration of ??Bottom-Up?? approach for measurement uncertainty evaluation of acetic acid in fermentation broths is also provided. The major sources of uncertainty of the result of measurement were identified and the combined uncertainty was calculated. Our analytical protocol allowed us to quantify acetic acid in fermentation broths in mass concentrations up to 75?g?L?1 with satisfactory recovery (102.3%) and repeatability lower than 2%. We also estimated within-laboratory reproducibility over 3-month period, which was 2.3%. We proved that the method was selective for the measurement of mass concentration of acetic acid in fermentation broths. Measurement uncertainty of results was evaluated to be 6.2% with 95% confidence level. After validation and measurement uncertainty evaluation steps, results obtained showed that the method can be applied to efficiently monitor fermentation processes. 相似文献
4.
Watanabe E Miyake S Ito S Baba K Eun H Ishizaka M Endo S 《Journal of chromatography. A》2006,1129(2):273-282
This work describes the analytical performance of the enzyme-linked immunosorbent assay (ELISA) for the fungicide chlorothalonil to effectively exploit as a simple and rapid detection system for pesticide residue on the scenes of the agricultural production and distribution. This ELISA represents the satisfactory analytical characteristics (I50 value, 0.34 ng/g; limit of detection, 0.052 ng/g) to detect chlorothalonil at the regulatory values or thereabout in a sample. Noticeable cross-reactivities were shown with two fungicides, fthalide (58.8%) and pentachloronitrobenzene (quintozene) (20.0%), and some non-agrochemicals such as tetrachloroterephthalonitrile (96.8%) and tetrachlorophthalonitrile (68.3%). The influence of three organic solvents (methanol, acetone, and acetonitrile) used as extractants for chlorothalonil residue was evaluated, with the result that methanol was the most suitable solvent for the ELISA, and the final concentration in the well could be up to 5% (v/v) without any negative influence on the ELISA. It has been possible to directly analyze chlorothalonil residue only by giving dilution of each sample extract with water prior to the ELISA analysis. The average recovery values from the spiked samples by the ELISA were between 101.7 and 113.6% with the average coefficients of variation between 2.6 and 5.9%. Although the results obtained from the ELISA correlated well with those from the reference GC/MS methods for all agricultural samples (r>0.98), the linear function inclined to the ELISA results because of loss during complex sample preparations for GC/MS analysis. Nevertheless, the results demonstrated that the proposed ELISA is a reliable, cost-effective, and rapid quantitative method for chlorothalonil residue. 相似文献
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Software support for the Nordtest method of measurement uncertainty evaluation is described. According to the Nordtest approach, the combined measurement uncertainty is broken down into two main components??the within-laboratory reproducibility (intermediate precision) s Rw and the uncertainty due to possible laboratory bias u(bias). Both of these can be conveniently estimated from validation and quality control data, thus significantly reducing the need for performing dedicated experiments for estimating detailed uncertainty contributions and thereby making uncertainty estimation easier for routine laboratories. An additional merit of this uncertainty estimation approach is that it reduces the danger of underestimating the uncertainty, which continues to be a problem at routine laboratories. The described software tool??MUkit (measurement uncertainty kit)??fully reflects the versatility of the Nordtest approach: it enables estimating the uncertainty components from different types of data, and the data can be imported using a variety of means such as different laboratory data systems and a dedicated web service as well as manual input. Prior to the development of the MUkit software, a laboratory survey was carried out to identify the needs of laboratories related to uncertainty estimation and other quality assurance procedures, as well as their needs for a practical tool for the calculation of measurement uncertainty. 相似文献
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Hasegawa H Shinohara Y Hashimoto T Matsuda R Hayashi Y 《Journal of chromatography. A》2006,1136(2):226-230
An equation is theoretically derived which describes the relative standard deviation (RSD) of the amount ratios of analyte to its isotope-labeled variant in gas chromatography/mass spectrometry (GC/MS) using the stable isotope dilution method. The determination of methyltestosterone is taken as an example. The uncertainty equation proposed is justified by comparing the theoretical RSD values with the experimental RSD values obtained by replication over a wide range of analyte amount. The detection limit and quantitation limit are estimated from the continuous plot (precision profile) of the theoretical RSD against analyte amount. 相似文献
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A highly accurate gas chromatographic analytical method has been developed for the determination of the composition of gas mixtures. It was tested using a reference gas as an example consisting of 3.5% of CO, 14% of CO2, 0.2% of propane and residual N2 intended for the use in vehicle emission measurements. The method is based on comparison measurements with samples of a calibration gas, whose composition is iteratively adapted to that of the sample investigated using a gravimetric gas mixing method. For the gas chromatographic measurement, a molecular sieve column and a polymer column are used in parallel and in isothermal operation. All gas components can be determined by a single gas chromatographic measurement, and the relative uncertainty of measurement achievable is ?0.4%. 相似文献
11.
A new isotope dilution mass spectrometry (IDMS) method for high-accuracy quantitative analysis of gases has been developed and validated by the analysis of standard mixtures of carbon dioxide in nitrogen. The method does not require certified isotopic reference materials and does not require direct measurements of the highly enriched spike. The relative uncertainty of the method is shown to be 0.2%. Copyright Crown copyright 2003. Reproduced with the permission of Her Majesty's Stationery Office. 相似文献
12.
Bojana Beljkaš Jovana Matić Ivan Milovanović Pavle Jovanov Aleksandra Mišan Ljubiša Šarić 《Accreditation and quality assurance》2010,15(10):555-561
The objective of this research was to test suitability of the Dumas combustion method to completely substitute the Kjeldahl
method in routine laboratory determination of crude protein content in cereals and oilseeds. The validation of the method
demonstrated that it is able to determine crude protein content in cereals and oilseeds in an efficient and accurate manner,
with a detection limit w(N) = 0.006%, quantification limit w(N) = 0.019%, repeatability precision RSD
r = 0.41%, intra-laboratory reproducibility precision RSD
R = 0.74%, trueness, expressed in terms of bias b = 0.43%, and linear response between (2.36–19.2) mg N. Measurement uncertainty, expressed as relative expanded uncertainty
(coverage factor k = 2, confidence level 95%), was calculated from validation data (U
rel = 2.24%). In order to examine the relationship between two methods, 15 cereal grain and oilseed samples were analyzed using
Dumas and Kjeldahl procedure. The Kjeldahl procedure gave slightly lower w(N) values than the Dumas procedure: w
K(N) = 0.9905 w
D(N) = 0.0376 (R
2
= 0.9996). Relative standard deviations and results of homogeneity test obtained during analysis of complex cereal products
(cereal breakfast and muesli bars) show that the Dumas combustion method may be less suitable for analysis of such samples
compared to Kjeldahl method. 相似文献
13.
A highly accurate gas chromatographic analytical method has been developed for the determination of the composition of gas
mixtures. It was tested using a reference gas as an example consisting of 3.5% of CO, 14% of CO2, 0.2% of propane and residual N2 intended for the use in vehicle emission measurements. The method is based on comparison measurements with samples of a calibration
gas, whose composition is iteratively adapted to that of the sample investigated using a gravimetric gas mixing method. For
the gas chromatographic measurement, a molecular sieve column and a polymer column are used in parallel and in isothermal
operation. All gas components can be determined by a single gas chromatographic measurement, and the relative uncertainty
of measurement achievable is ?0.4%.
Received: 6 March 1996/Revised: 30 May 1996/Accepted: 6 June 1996 相似文献
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A method for separation and quantitative determination of the iodosulfuron-methyl-sodium in water samples by high-performance
liquid chromatography (HPLC) was developed and in-house validated in order to demonstrate its performance for monitoring of
heterogeneous photocatalytic elimination of the herbicide iodosulfuron-methyl-sodium from water. Surface and ground water
samples were used to demonstrate its selectivity, detection and quantification limits, linearity, trueness and precision.
In addition, stability of iodosulfuron-methyl-sodium was studied in function of temperature and time. Method accuracy was
quantified through measurement uncertainty estimate based on method validation data. The paper gives practical and easy to
follow guidance on how uncertainty estimates can be obtained from method validation experiments. It shows that, if properly
planned and executed, key precision and trueness studies undertaken for validation purposes can also provide much of the data
needed to produce an estimate of measurement uncertainty. Our analytical protocol allowed us to quantify iodosulfuron-methyl-sodium
in ground water and surface water in concentration level between 2.50–50.0 μmol L−1 with satisfactory recoveries (99–104%) and repeatability lower or equal than 0.3% for all the matrices. We also estimated
within-laboratory reproducibility over 3-month period, which was 0.7%. We proved that the method was selective for determination
of iodosulfuron-methyl-sodium in the relevant matrices. Measurement uncertainty of results was evaluated to be 4.0% with 95%
confidence level. After validation and measurement uncertainty evaluation steps, results obtained showed that the method can
be applied to efficiently monitor heterogenous photocatalytic degradation of the herbicide iodosulfuron-methyl-sodium. 相似文献
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The implementation of quality systems in analytical laboratories has now, in general, been achieved. While this requirement significantly modified the way that the laboratories were run, it has also improved the quality of the results. The key idea is to use analytical procedures which produce results that fulfil the users needs and actually help when making decisions. This paper presents the implications of quality systems on the conception and development of an analytical procedure. It introduces the concept of the lifecycle of a method as a model that can be used to organize the selection, development, validation and routine application of a method. It underlines the importance of method validation, and presents a recent approach based on the accuracy profile to illustrate how validation must be fully integrated into the basic design of the method. Thanks to the -expectation tolerance interval introduced by Mee (Technometrics (1984) 26(3):251–253), it is possible to unambiguously demonstrate the fitness for purpose of a new method. Remembering that it is also a requirement for accredited laboratories to express the measurement uncertainty, the authors show that uncertainty can be easily related to the trueness and precision of the data collected when building the method accuracy profile. 相似文献
18.
Development and validation of a liquid chromatography method for analysis of colistin sulphate 总被引:2,自引:0,他引:2
Summary The peptide antibiotic Colistin has been successfully separated into more than thirty components on a YMC-Pack Pro, C-18 column
with a mobile phase of acetonitrile—sodium sulphate (0.7% m/v)—phosphoric acid (6.8% v/v dilution of 85% m/m H3PO4)—water (21.5∶50∶5∶23.5) at 1.0 mL per min and detection at 215 nm. Baseline resolution of the major components, colistin
A and B, and many minor components was obtained. Robustness was evaluated by performing a full-factorial design experiment.
The method showed good selectivity, repeatability, linearity and sensitivity. 相似文献
19.
Consistent treatment of measurement bias, including the question of whether or not to correct for bias, is essential for the comparability of measurement results. The case for correcting for bias is discussed, and it is shown that instances in which bias is known or suspected, but in which a specific correction cannot be justified, are comparatively common. The ISO Guide to the Expression of Uncertainty in Measurement does not provide well for this situation. It is concluded that there is a need for guidance on handling cases of uncorrected bias. Several different published approaches to the treatment of uncorrected bias and its uncertainty are critically reviewed with regard to coverage probability and simplicity of execution. On the basis of current studies, and taking into account testing laboratory needs for a simple and consistent approach with a symmetric uncertainty interval, we conclude that for most cases with large degrees of freedom, linear addition of a bias term adjusted for exact coverage ("U(e)") as described by Synek is to be preferred. This approach does, however, become more complex if degrees of freedom are low. For modest bias and low degrees of freedom, summation of bias, bias uncertainty and observed value uncertainty in quadrature ("RSSu") provides a similar interval and is simpler to adapt to reduced degrees of freedom, at the cost of a more restricted range of application if accurate coverage is desired. 相似文献