1、raising standards worldwideNO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAWBSI Standards PublicationPD CEN/TR 10350:2013Analysis of steels and irons Internal laboratory procedurefor checking the accuracy ofan analytical method by usingCertified Reference MaterialsPD CEN/TR 1035
2、0:2013 PUBLISHED DOCUMENTNational forewordThis Published Document is the UK implementation ofCEN/TR 10350:2013. It supersedes PD CEN/TR 10350:2009 which iswithdrawn.The UK participation in its preparation was entrusted to TechnicalCommittee ISE/102, Methods of Chemical Analysis for Iron and Steel. A
3、 list of organizations represented on this committee can beobtained on request to its secretary.This publication does not purport to include all the necessaryprovisions of a contract. Users are responsible for its correctapplication. The British Standards Institution 2013.Published by BSI Standards
4、Limited 2013.ISBN 978 0 580 77710 3 ICS 77.040.30 Compliance with a British Standard cannot confer immunity fromlegal obligations.This Published Document was published under the authority of theStandards Policy and Strategy Committee on 31 March 2013. Amendments issued since publicationDate T e x t
5、a f f e c t e dPD CEN/TR 10350:2013TECHNICAL REPORT RAPPORT TECHNIQUE TECHNISCHER BERICHT CEN/TR 10350 February 2013 ICS 77.040.30 Supersedes CEN/TR 10350:2009English Version Analysis of steels and irons - Internal laboratory procedure for checking the accuracy of an analytical method by using Certi
6、fied Reference Materials Analyse des aciers et des fontes - Procdure de contrle intralaboratoire de lexactitude dune mthode analytique au moyen de Matriaux de Rfrence Certifis Analyse von Stahl und Eisen - Laboratoriumsinternes Verfahren zur berprfung der Richtigkeit eines - Analysenverfahrens mit H
7、ilfe zertifizierter Referenzmaterialien This Technical Report was approved by CEN on 16 July 2012. It has been drawn up by the Technical Committee ECISS/TC 102. CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, Fo
8、rmer Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and United Kingdom. EUROPEAN COMMITTEE FOR STANDARDIZATION COMI
9、T EUROPEN DE NORMALISATION EUROPISCHES KOMITEE FR NORMUNG Management Centre: Avenue Marnix 17, B-1000 Brussels 2013 CEN All rights of exploitation in any form and by any means reserved worldwide for CEN national Members. Ref. No. CEN/TR 10350:2013: EPD CEN/TR 10350:2013CEN/TR 10350:2013 (E) 2 Conten
10、ts Page Foreword . 3 Introduction 4 1 Scope 5 2 Principle 5 3 Terms and definitions 5 4 Procedure . 8 4.1 General . 8 4.2 Number of replicate determinations 8 4.3 CRMs 9 4.4 Determinations . 9 5 Evaluation of precision 10 5.1 Procedure . 10 5.2 Evaluation . 11 6 Assessment of the trueness 11 6.1 Pro
11、cedure . 11 6.2 Assessment 12 7 Conclusion . 12 Annex A (informative) Symbols used . 13 Annex B (informative) Table of the 2distribution . 14 Annex C (informative) Examples 15 Bibliography 23 PD CEN/TR 10350:2013CEN/TR 10350:2013 (E) 3 Foreword This document (CEN/TR 10350:2013) has been prepared by
12、Technical Committee ECISS/TC 102 “Methods of chemical analysis for iron and steel”, 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 of patent rights. CEN and/or CENELEC shall not be held responsible for iden
13、tifying any or all such patent rights. This document supersedes CEN/TR 10350:2009. In comparison with the previous version of CEN/TR 10350, the following significant technical changes were made: Definition 3.12: Correction of the definition for “uncertainty of the certified values”; Table C.7: Corre
14、ction of the confidence level for 2; C.2.3.3: Correction of the sample label: G instead of A. PD CEN/TR 10350:2013CEN/TR 10350:2013 (E) 4 Introduction This Technical Report defines a procedure for checking, in each specific laboratory, the accuracy of an analytical method by the application of stati
15、stical principles to the analytical results obtained on Certified Reference Materials (CRMs). This Technical Report is an adaptation of ISO Guide 33:2000 mostly for the specific cases where EURONORM-CRMs are used for checking, in an intralaboratory context, the accuracy of an analytical method. Neve
16、rtheless, it may be adopted in any other case where CRMs selected have similar quality levels to those of EURONORM-CRMs. PD CEN/TR 10350:2013CEN/TR 10350:2013 (E) 5 1 Scope The present statistical procedure describes how to check results for absence of bias by comparison of these analytical results
17、with those obtained during the certification 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
18、 the repeatability and/or the intermediate 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. F
19、or the purpose of this Technical 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 This Technical Report does not describe the use of CRMs as calibrants, this subject being treated in ISO Guide 32. 2 P
20、rinciple This Technical Report 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
21、 by the selected CRMs. Nevertheless 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
22、of an analytical method as 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 ma
23、king this comparison. Moreover, adjustment values chosen in advance by the laboratory, according to economic or technical limitations or stipulations are also taken into account. 3 Terms and definitions For the purposes of this document, the following terms and definitions apply. 3.1 certified refer
24、ence material CRM reference material 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
25、value includes qualitative attributes 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 Gui
26、de 31 gives guidance on the contents of certificates. NOTE 4 VIM has an analogous definition (ISO/IEC Guide 99:2007, 5.14). PD CEN/TR 10350:2013CEN/TR 10350:2013 (E) 6 SOURCE: ISO Guide 30; Amendment 1:2008 3.2 reference material RM material, sufficiently homogeneous and stable with respect to one o
27、r 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 Uses may include the calibration of a measurement system,
28、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 definition (ISO/IEC Guide 99:2007, 5.13), but restricts the
29、 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”. SOURCE: ISO Guide 30; Amendment 1:2008 3.3 accuracy closeness of agreement
30、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 and common systematic error or bias component. NO
31、TE 3 Accuracy refers to a combination of trueness and precision. SOURCE: 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 random error. There may be one or more syst
32、ematic 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 number of repeated measurements. The erro
33、r 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. SOURCE: ISO 3534-2:2006, 3.3.2 3.5 precision closeness of agreement between independent test/measu
34、rement 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. NOTE 2 The measure of precision is usually expressed in terms of imprecision and computed as a standard deviation of th
35、e test results or measurement results. Less precision is reflected by a larger standard deviation. PD CEN/TR 10350:2013CEN/TR 10350:2013 (E) 7 NOTE 3 Quantitative measures of precision depend critically on the stipulated conditions. Repeatability conditions and reproducibility conditions are particu
36、lar sets of extreme stipulated conditions. SOURCE: ISO 3534-2:2006, 3.3.4 3.6 repeatability precision under repeatability conditions SOURCE: ISO 3434-2:2006, 3.3.5 3.7 repeatability conditions conditions where independent test/measurement results are obtained with the same method on identical test/m
37、easurement 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 measurement procedure or test procedure; b) the same operator; c) the same measuring or test equipment used under th
38、e same conditions; d) the same location; e) repetition over a short period of time. SOURCE: ISO 3434-2:2006, 3.3.6 3.8 reproducibility precision under reproducibility conditions NOTE 1 Reproducibility can be expressed quantitatively in terms of the dispersion characteristics of the results. NOTE 2 R
39、esults are usually understood to be corrected results. NOTE 3 This definition is not used in the present document: it is given only to clarify the next item. SOURCE: ISO 3534-2:2006, 3.3.10 3.9 reproducibility conditions observation conditions where independent test/measurement results are obtained
40、with the same method on identical test/measurement items in different test or measurement facilities with different operators using different equipment SOURCE: ISO 3534-2:2006, 3.3.11 3.10 intermediate precision precision under intermediate precision conditions SOURCE: ISO 3534-2:2006, 3.3.15 PD CEN
41、/TR 10350:2013CEN/TR 10350:2013 (E) 8 3.11 intermediate precision conditions conditions where test results or measurement 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
42、 four elements to the operating condition: time, calibration, operator and equipment. NOTE 2 A test house is an example of a test facility. A metrology laboratory is an example of a measurement facility. SOURCE: ISO 3534-2:2006, 3.3.16 3.12 uncertainty of the certified values in the particular case
43、of EURONORM-CRMs, the uncertainty of each certified value is expressed as the 95 % half-width confidence interval “C(95 %)“ of the mean of the intralaboratory means Note 1 to entry: It is calculated from Formula (1): nS t%) C(95M= (1) where t is the Students value at the desired probability with n-1
44、 degrees of freedom; SMis the standard deviation of the intralaboratory means; n is the number of acceptable intralaboratory mean values. Note 2 to entry: This definition is not used in the present document: it is only given for clarification. 4 Procedure 4.1 General The analytical method for the me
45、asurement 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 range of the analytical method, which shall at least be bounded with low and high content, and i
46、f 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 intended to be analysed. For example, if the analytical method concerns the determination of copper in
47、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. 4.2 Number of replicate determinations The number of replicate determinations required, n0, depen
48、ds 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. PD CEN/TR 10350:2013CEN/TR 10350:2013 (E) 9 Table 1 shows the relation between the degrees of freedom (where in this case = n
49、 - 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 of the analytical results will pass the appropriate 2-test at = 0,05 is no more than 1 % when within-laboratory standard deviation, W1, of the analytical method is equal or larger than 2,85 times the required value of W0. The user needs to establish, before the ana
