BS PD CEN TR 10350-2009 Analysis of steels nand irons — Internal nlaboratory procedure nfor checking the naccuracy of an nanalytical method nby using Certified nReference Materials.pdf

1、PD CEN/TR10350:2009ICS 77.040.30NO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAWPUBLISHED DOCUMENTAnalysis of steelsand irons Internallaboratory procedurefor checking theaccuracy of ananalytical methodby using CertifiedReference MaterialsLicensed Copy: Wang Bin, ISO/EXCHANGE CH

2、INA STANDARDS, 09/10/2010 09:13, Uncontrolled Copy, (c) BSIThis Published Documentwas published under theauthority of the StandardsPolicy and StrategyCommittee on 30 June2010 BSI 2010ISBN 978 0 580 54493 4Amendments/corrigenda issued since publicationDate CommentsPD CEN/TR 10350:2009National forewor

3、dThis Published Document is the UK implementation of CEN/TR10350:2009.The UK participation in its preparation was entrusted to TechnicalCommittee ISE/102, Methods of Chemical Analysis for Iron and Steel.A list of organizations represented on this committee can be obtained onrequest to its secretary.

4、This publication does not purport to include all the necessary provisionsof a contract. Users are responsible for its correct application.Compliance with a British Standard cannot confer immunityfrom legal obligations.Licensed Copy: Wang Bin, ISO/EXCHANGE CHINA STANDARDS, 09/10/2010 09:13, Uncontrol

5、led Copy, (c) BSIPD CEN/TR 10350:2009TECHNICAL REPORT RAPPORT TECHNIQUE TECHNISCHER BERICHT CEN/TR 10350 December 2009 ICS 77.040.30 English Version Analysis of steels and irons - Internal laboratory procedure for checking the accuracy of an analytical method by using Certified Reference Materials A

6、nalyse des aciers et des fontes - Mthode de contrle intralaboratoire de lexactitude dune procdure analytique au moyen de Matriaux de Rfrence Certifis Analyse von Stahl und Eisen - Laboratoriumsinternes Verfahren zur berprfung der Richtigkeit eines Analysenverfahrens mit Hilfe zertifizierter Referenz

7、materialien This Technical Report was approved by CEN on 26 October 2009. It has been drawn up by the Technical Committee ECISS/TC 20. CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Ice

8、land, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom. EUROPEAN COMMITTEE FOR STANDARDIZATION COMIT EUROPEN DE NORMALISATION EUROPISCHES KOMITEE FR NORMUNG Management Centre: Avenu

9、e Marnix 17, B-1000 Brussels 2009 CEN All rights of exploitation in any form and by any means reserved worldwide for CEN national Members. Ref. No. CEN/TR 10350:2009: ELicensed Copy: Wang Bin, ISO/EXCHANGE CHINA STANDARDS, 09/10/2010 09:13, Uncontrolled Copy, (c) BSIPD CEN/TR 10350:2009CEN/TR 10350:

10、2009 (E) 2 Contents Page Foreword 3Introduction .41 Scope 52 Principle 53 Definitions 54 Procedure .84.1 General 84.2 Number of replicate determinations 84.3 CRMs .94.4 Determinations .95 Evaluation of precision 105.1 Procedure 105.2 Evaluation 116 Assessment of the trueness 116.1 Procedure 116.2 As

11、sessment . 127 Conclusion 12Annex A (informative) Symbols used . 13Annex B (informative) Table of the 2distribution 14Annex C (informative) Examples 15Bibliography . 23Licensed Copy: Wang Bin, ISO/EXCHANGE CHINA STANDARDS, 09/10/2010 09:13, Uncontrolled Copy, (c) BSIPD CEN/TR 10350:2009CEN/TR 10350:

12、2009 (E) 3 Foreword This document (CEN/TR 10350:2009) has been prepared by Technical Committee ECISS/TC 20 “Methods of chemical analysis of ferrous products”, the secretariat of which is held by SIS. Attention is drawn to the possibility that some of the elements of this document may be the subject

13、of patent rights. CEN and/or CENELEC shall not be held responsible for identifying any or all such patent rights. This document supersedes IC 5:1986. Licensed Copy: Wang Bin, ISO/EXCHANGE CHINA STANDARDS, 09/10/2010 09:13, Uncontrolled Copy, (c) BSIPD CEN/TR 10350:2009CEN/TR 10350:2009 (E) 4 Introdu

14、ction The aim of this Technical Report is to define a procedure for checking, in each specific laboratory, the accuracy of an analytical method by the application of statistical principles to the analytical results obtained on Certified Reference Materials (CRMs). This Technical Report is an adaptat

15、ion of ISO Guide 33 mostly for the specific cases where EURONORM-CRMs are used for checking, in an intralaboratory context, the accuracy of an analytical method. Nevertheless, it may be adopted in any other case where CRMs selected have similar quality levels to those of EURONORM-CRMs. Licensed Copy

16、: Wang Bin, ISO/EXCHANGE CHINA STANDARDS, 09/10/2010 09:13, Uncontrolled Copy, (c) BSIPD CEN/TR 10350:2009CEN/TR 10350:2009 (E) 5 1 Scope The present statistical procedure describes how to check results for absence of bias by comparison of these analytical results with those obtained during the cert

17、ification of CRMs. If the resulting data confirm the absence of bias, the method may be considered accurate when applied to all steels and irons whose composition ranges are adequately covered or bounded by the CRMs used. The resulting data give also an estimate of the repeatability and/or the inter

18、mediate precision (“intralaboratory reproducibility“) for the CRMs used. The comparison of these analytical data with the repeatability data obtained during the certification may also be performed depending on the strict purpose of the method under consideration. NOTE 1 For the purpose of this Techn

19、ical Report, the use of existing CRMs is essential for the assessment of the trueness, but it may be only indicative for the other statistical data. NOTE 2 This Technical Report does not describe the use of CRMs as calibrants, this subject being treated in ISO Guide 32. 2 Principle This Technical Re

20、port describes a procedure for checking an analytical method used in a specific laboratory by using data obtained from the analysis of CRMs. The absence of bias ascertained with CRMs can be extended to the trueness of further analytical samples adequately covered or bounded by the selected CRMs. Nev

21、ertheless it should be underlined that this Technical Report is not appropriate for the assessment of the repeatability and/or the intermediate precision data of the further analytical samples to be tested by the analytical method under consideration. Checking the trueness of an analytical method as

22、 applied by a specific laboratory involves the comparison of the mean value of the analytical results obtained by using CRMs with the certified value of each CRM selected. The standard deviation of the intralaboratory means of the selected CRMs is taken into account when making this comparison. More

23、over, adjustment values chosen in advance by the laboratory, according to economic or technical limitations or stipulations are also taken into account. 3 Definitions For the purposes of this document, the following terms and definitions apply. 3.1 certified reference material CRM reference material

24、 characterized by a metrologically valid procedure for one or more specified properties, accompanied by a certificate that provides the value of the specified property, its associated uncertainty, and a statement of metrological traceability NOTE 1 The concept of value includes qualitative attribute

25、s such as identity or sequence. Uncertainties for such attributes may be expressed as probabilities. NOTE 2 Metrologically valid procedures for the production and certification of reference materials are given in, among others, ISO Guides 34 and 35. NOTE 3 ISO Guide 31 gives guidance on the contents

26、 of certificates. Licensed Copy: Wang Bin, ISO/EXCHANGE CHINA STANDARDS, 09/10/2010 09:13, Uncontrolled Copy, (c) BSIPD CEN/TR 10350:2009CEN/TR 10350:2009 (E) 6 NOTE 4 VIM has an analogous definition (ISO/IEC Guide 99:2007, 5.14). ISO Guide 30; Amendment 1:2008 3.2 reference material RM material, su

27、fficiently homogeneous and stable with respect to one or more specified properties, which has been established to be fit for its intended use in a measurement process NOTE 1 “RM“ is a generic term. NOTE 2 Properties can be quantitative or qualitative, e.g. identity of substances or species. NOTE 3 U

28、ses may include the calibration of a measurement system, assessment of a measurement procedure, assigning values to other materials, and quality control. NOTE 4 A single RM cannot be used for both calibration and validation of results in the same measurement procedure. NOTE 5 VIM has an analogous de

29、finition (ISO/IEC Guide 99:2007, 5.13), but restricts the term “measurement” to apply to quantitative values and not to qualitative properties. However, NOTE 3 of ISO/IEC Guide 99:2007, 5.13, specifically includes the concept of qualitative attributes, called “nominal properties”. ISO Guide 30; Amen

30、dment 1:2008 3.3 accuracy closeness of agreement between a test result and the true value NOTE 1 In practice, the accepted reference value is substituted for the true value. NOTE 2 The term “accuracy“, when applied to a set of test or measurement results, involves a combination of random components

31、and common systematic error or bias component. NOTE 3 Accuracy refers to a combination of trueness and precision. ISO 3534-2:2006, 3.3.1 3.4 bias difference between the expectation of a test result or a measurement result and a true value NOTE 1 Bias is the total systematic error as contrasted to ra

32、ndom error. There may be one or more systematic error components contributing to the bias. A larger systematic difference from the true value is reflected by a larger bias value. NOTE 2 The bias of a measuring instrument is normally estimated by averaging the error of indication over an appropriate

33、number of repeated measurements. The error of indication is the “indication of a measuring instrument minus a true value of the corresponding input quantity“. NOTE 3 In practice, the accepted reference value is substituted for the true value. ISO 3534-2:2006, 3.3.2 3.5 precision closeness of agreeme

34、nt between independent test/measurement results obtained under stipulated conditions NOTE 1 Precision depends only on the distribution of random errors and does not relate to the true value or the specified value. Licensed Copy: Wang Bin, ISO/EXCHANGE CHINA STANDARDS, 09/10/2010 09:13, Uncontrolled

35、Copy, (c) BSIPD CEN/TR 10350:2009CEN/TR 10350:2009 (E) 7 NOTE 2 The measure of precision is usually expressed in terms of imprecision and computed as a standard deviation of the test results or measurement results. Less precision is reflected by a larger standard deviation. NOTE 3 Quantitative measu

36、res of precision depend critically on the stipulated conditions. Repeatability conditions and reproducibility conditions are particular sets of extreme stipulated conditions. ISO 3534-2:2006, 3.3.4 3.6 repeatability precision under repeatability conditions ISO 3434-2:2006, 3.3.5 3.7 repeatability co

37、nditions conditions where independent test/measurement results are obtained with the same method on identical test/measurement items in the same test or measuring facility by the same operator using the same equipment within short intervals of time NOTE Repeatability conditions include: a) the same

38、measurement procedure or test procedure; b) the same operator; c) the same measuring or test equipment used under the same conditions; d) the same location; e) repetition over a short period of time. ISO 3434-2:2006, 3.3.6 3.8 reproducibility precision under reproducibility conditions NOTE 1 Reprodu

39、cibility can be expressed quantitatively in terms of the dispersion characteristics of the results. NOTE 2 Results are usually understood to be corrected results. ISO 3534-2:2006, 3.3.10 NOTE 3 This definition is not used in the present document: it is given only to clarify the next item. 3.9 reprod

40、ucibility conditions observation conditions where independent test/measurement results are obtained with the same method on identical test/measurement items in different test or measurement facilities with different operators using different equipment ISO 3534-2:2006, 3.3.11 3.10 intermediate precis

41、ion precision under intermediate precision conditions ISO 3534-2:2006, 3.3.15 Licensed Copy: Wang Bin, ISO/EXCHANGE CHINA STANDARDS, 09/10/2010 09:13, Uncontrolled Copy, (c) BSIPD CEN/TR 10350:2009CEN/TR 10350:2009 (E) 8 3.11 intermediate precision conditions conditions where test results or measure

42、ment results are obtained with the same method, on identical test/measurement items in the same test or measurement facility, under some different operating condition NOTE 1 There are four elements to the operating condition: time, calibration, operator and equipment. NOTE 2 A test house is an examp

43、le of a test facility. A metrology laboratory is an example of a measurement facility. ISO 3534-2:2006, 3.3.16 3.12 uncertainty of the certified values in the particular case of EURONORM-CRMs, 95 % half-width confidence interval “C (95 %)“ of the mean of the intralaboratory means NOTE 1 It is calcul

44、ated from Equation (1): nS t%) C(95M= (1) where t is the Students value at the desired probability with n-1 degrees of freedom; SMis the standard deviation of the intralaboratory means; n is the number of acceptable intralaboratory mean values. NOTE 2 This definition is not used in the present docum

45、ent: it is only given for clarification. 4 Procedure 4.1 General The analytical method for the measurement shall be fixed, i.e. a written document shall exist laying down all the details. There shall be no changes to the method during the course of the experiment. CRMs to be selected shall cover the

46、 range of the analytical method, which shall at least be bounded with low and high content, and if possible, shall include an intermediate content. Furthermore, it should be possible to extend the choice of CRMs to cover similar matrices representing the compositions of the analytical samples intend

47、ed to be analysed. For example, if the analytical method concerns the determination of copper in low alloy steel samples with a nickel content of about 0,01 % and also in samples having a nickel content of about 1 % it is advisable to test the method within its full range for both kind of matrices.

48、4.2 Number of replicate determinations The number of replicate determinations required, n0, depends mainly on the values of and and the alternative hypothesis chosen for the assessment of the precision. NOTE is the significance level and is the type II error probability. Licensed Copy: Wang Bin, ISO

49、/EXCHANGE CHINA STANDARDS, 09/10/2010 09:13, Uncontrolled Copy, (c) BSIPD CEN/TR 10350:2009CEN/TR 10350:2009 (E) 9 Table 1 shows the relation between the degrees of freedom (where in this case = n - 1) and the ratio of the within-laboratory standard deviation of the analytical method, W1, and the required value of the within-laboratory standard deviation, W0, for various values of at = 0,05. For example, for n = 10 the probability that the variance o