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1、J IS JAPANESE I NDUSTRIAL STANDARD Translated and Published by Japanese Standards Association JIS Q 0033 z20o2 (IS0 Guide 33 : 2000) Uses of certified reference materials ICs 03.120.10; 71.040.30 Reference number : JIS Q 0033 : 2002 (E) PROTECTED BY COPYRIGHT Copyright Japanese Standards Association
2、 Provided by IHS under license with JSALicensee=IHS Employees/1111111001, User=Wing, Bernie Not for Resale, 03/16/2007 01:38:45 MDTNo reproduction or networking permitted without license from IHS -,-,- Q 0033 : 2002 (IS0 Guide 33 : 2000) Foreword This translation has been made based on the original
3、Japanese Industrial Standard revised by the Minister of Economy, Trade and Industry through deliberations at the Japanese Industrial Standards Committee in accordance with the Industrial Standardization Law. Consequently JIS Q 0033:1997 is replaced with JIS Q 0033:2002. This revision followed the re
4、vision of IS0 Guide 33. Date of Establishment: 1997-03-20 Date of Revision: 2002-03-20 Date of Public Notice in Official Gazette: 2002-03-20 Investigated by: Japanese Industrial Standards Committee Conformity Assessment Board JIS Q 0033: 2002, First English edition published in 2003-03 Translated an
5、d published by: Japanese Standards Association 4-1-24, Akasaka, Minato-ku, Tokyo, 107-8440 JAPAN In the event of any doubts arising as to the contents, the original JIS is to be the final authority. O JSA 2003 All rights reserved. Unless otherwise specified, no part of this publication may be reprod
6、uced or utilized in any form or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from the publisher. Printed in Japan PROTECTED BY COPYRIGHT Copyright Japanese Standards Association Provided by IHS under license with JSALicensee=IHS Employee
7、s/1111111001, User=Wing, Bernie Not for Resale, 03/16/2007 01:38:45 MDTNo reproduction or networking permitted without license from IHS -,-,- Q 0033 : 2002 (IS0 Guide 33 : 2000) Contents Introduction . 1 2 2.1 2.2 2.3 2.4 2.5 2.6 2.7 2.8 2.9 2.10 2.11 2.12 2.13 2.14 2.15 2.16 2.17 2.18 2.19 2.20 3 3
8、.1 3.2 4 4.1 4.2 5 5.1 5.2 5.3 Scope Terms and definitions . measurement process . influence quantity reference material. RM certified reference material. CRM . precision . repeatability repeatability standard deviation . repeatability limit, T reproducibility . repeatability conditions . reproducib
9、ility conditions reproducibility limit, R bias accuracy trueness uncertainty . estimation estimate estimator null hypothesis Symbols and subscripts Symbols Subscripts Statistical considerations . Basic assumptions Decision errors The role of certified reference materials in measurement science Gener
10、al . The role of certified reference materials in the storage and transfer of information on property values . Use of certified reference materials for measurement traceability Page 1 3 3 3 4 4 4 5 5 5 5 5 5 5 5 6 6 6 6 6 6 6 6 6 6 7 7 7 7 8 8 8 9 (i PROTECTED BY COPYRIGHT Copyright Japanese Standar
11、ds Association Provided by IHS under license with JSALicensee=IHS Employees/1111111001, User=Wing, Bernie Not for Resale, 03/16/2007 01:38:45 MDTNo reproduction or networking permitted without license from IHS -,-,- Q 0033 : 2002 (IS0 Guide 33 : 2000) 5.4 5.4.1 5.4.2 5.4.3 The role of reference mate
12、rials in the International Systems of units (SI) . 10 Dependence of the SI base units on substances and materials 10 Obtaining of derived SI units with the aid of reference materials 10 Connection of analytical chemistry to the International System of units . 10 5.5 Defining and creating conventiona
13、l scales 11 5.5.1 General 11 5.5.2 The International Temperature Scale . 12 5.5.3 The pH scale . 13 5.5.4 The octane-number scale 13 6 Assessment of a measurement process 14 6.1.1 One laboratory 14 6.1 The cases to be considered . 14 6.1.2 Interlaboratory programme 14 6.2 Requirements of limits 14 6
14、.2.1 General 14 6.2.2 Legal limits . 14 6.2.3 Limits in accreditation schemes . 14 6.2.4 14 6.2.5 Limits from previous experience . 14 6.3 Choice of CRM 14 6.3.1 Relevance to the measurement procedure 15 6.3.2 Type of certification of CRM . 15 6.4 Experimental procedure 15 6.4.1 General 15 6.4.2 6.4
15、.2.1 General . 15 Limits given by the user of the procedure Check of precision and trueness of a measurement process by one laboratory . 15 6.4.2.2 Number of replicate measurements . 16 6.4.2.3 TheCRM . 16 6.4.2.4 Measurement . 16 6.4.2.5 Assessment of precision . 17 6.4.2.6 Assessment of trueness 1
16、8 6.4.2.7 19 6.4.3 6.4.3.1 General . 20 6.4.3.2 Number of participant laboratories, p , and number of replicate measurements per laboratory, n 20 Example - analysis for the iron content in iron ores Assessment of a measurement process by an interlaboratory measurement programme . 20 (ii) PROTECTED B
17、Y COPYRIGHT Copyright Japanese Standards Association Provided by IHS under license with JSALicensee=IHS Employees/1111111001, User=Wing, Bernie Not for Resale, 03/16/2007 01:38:45 MDTNo reproduction or networking permitted without license from IHS -,-,- Q 0033 : 2002 (IS0 Guide 33 : 2000) 6.4.3.3 Ex
18、periment . 6.4.3.3.1 General . 6.4.3.3.2 Check and distribution of the CRM 6.4.3.3.3 Measurement . 6.4.3.4 Assessment of precision 6.4.3.4.1 General . 6.4.3.4.2 Within-laboratory precision 6.4.3.4.3 Between-laboratories precision 6.4.3.5 Assessment of trueness 6.4.3.6 Example 6.4.3.7 Detailed proced
19、ure for computing the ideal combination of p and n 6.5 General remarks . 6.5.1 General 6.5.2 The CRM . 6.5.3 The measurement process Bibliography . 20 20 20 21 21 21 21 21 22 22 23 24 25 25 25 26 (iii) PROTECTED BY COPYRIGHT Copyright Japanese Standards Association Provided by IHS under license with
20、 JSALicensee=IHS Employees/1111111001, User=Wing, Bernie Not for Resale, 03/16/2007 01:38:45 MDTNo reproduction or networking permitted without license from IHS -,-,- JAPANESE INDUSTRIAL STANDARD JIS Q 0033 : 2002 (IS0 Guide 33 : 2000) Uses of certified reference materials Introduction This Japanese
21、 Industrial Standard has been prepared based on the second edition of IS0 Guide 33 Uses of certified reference materials published in 2000 without modifying the technical contents. Portions underlined with dots in this Standard are the matters not stated in the original Guide. Todays world of modern
22、 technology requires a large number of certified reference materials (CRMs) in widely diverse fields, and the demand for such materials is expected to increase. The preparation of a CRM is a time-consuming, meticulous and expensive endeavour and consequently it has not always been, and will continue
23、 not to be, possible to satisfy the demand for all types and quantities of CRMs. For this reason, CRMs should be used properly, Le. effectively, efficiently and economically. Certified reference materials should be used on a regular basis to ensure reliable measurements. However, in doing so, the ma
24、gnitude of the supply of that CRM, its relative cost, its availability (accessibility) and the measurement technique, be it destructive or non-destructive, should be considered. Also important to the user is the fact that the misuse of a CRM may not provide the intended information. Misuse of CRMs d
25、iffers from incorrect use. The user of a CRM is expected to be familiar with all information pertinent to the use of the CRM as specified in its certificate. He should comply with such factors as the period of validity of the CRM, the prescribed conditions for storage of the CRM, instructions for th
26、e use of the CRM, and specifications for validity of the certified properties of the CRM. A CRM should not be used for a purpose other than that for which it was intended. Nevertheless, from time to time, when a user must resort to applying a CRM in an incorrect manner because of the unavailability
27、of a suitable CRM, he should be fully cognizant of the potential pitfalls and therefore assess his measurement output accordingly. There are many measurement processes in which CRMs are in general use but are replaceable by a host of working standards, such as homogeneous materials, previously analy
28、sed materials, pure compounds, solutions of pure elements, etc. Some examples are where only a “rough“ estimate of the trueness or precision of a method is sought, where “blind“ unknown check samples are used routinely in quality control programmes, and where only the variation in trueness or precis
29、ion of a method with some parameter such as time, analyst, instrument, etc., is being evaluated. The first example illustrates the use of a CRM in which the well-defined certified value and uncertainty of the CRM is under-utilized. The others illustrate the case in which a series of “one-time“ truen
30、ess and precision assessments are compared with one another. There is no need to base that comparison on a well-defined certified value and uncertainty of a CRM. The advantages in using CRMs are that the user has the means to assess the trueness and precision of his measurement method and establishe
31、s metrological traceability for his results. Whether the use of CRMs in these procedures is in fact “misuse“ depends largely on the availability and relative cost of the CRMs. Where CRMs are in short supply or very expensive, their use would indeed be misuse. However, for CRMs in ample supply or whe
32、re similar CRMs are available from one or more sources, it is strongly recommended that CRMs always be used instead of in-house standards because of the resultant enhanced confidence in the measurement output. PROTECTED BY COPYRIGHT Copyright Japanese Standards Association Provided by IHS under lice
33、nse with JSALicensee=IHS Employees/1111111001, User=Wing, Bernie Not for Resale, 03/16/2007 01:38:45 MDTNo reproduction or networking permitted without license from IHS -,-,- 2 Q 0033 : 2002 (IS0 Guide 33 : 2000) It is important that users remain aware that the preparation of in-house standards for
34、use instead of CRMs has an associated cost based on factors such as material cost, facility usage charges, personnel labour rates, etc., in which the material cost is in general the lowest. For some CRMs such as the complex compositional materials certified for chemical composition, the cost of prep
35、aring in-house standards to match the composition of real samples can exceed that of available CRMs. In these cases, the use of CRMs is recommended. The user should be aware of the potential misuse of CRMs as “blind“ unknown check samples in quality control programmes. Where there are only a few CRM
36、s in an area of expertise, they are easily recognized and they may therefore not satisfy the intended purpose. Moreover, the same CRM should never be used for both calibration purposes and as “blind“ unknown check sample in a measurement process. The misuse of CRMs can also occur when the user does
37、not fully take into account the uncertainty in the certified property. The combined standard uncertainty of a certified property of a CRM can have contributions from the inhomogeneity of the material, the within-laboratory uncertainty and, where applicable, the between- laboratory uncertainty. The l
38、evel of homogeneity defined for a CRM by the producer is dependent on both the statistical design used to evaluate it and the repeatability of the method of measurement. For certain CRMs, the level of homogeneity is valid for a test portion defined by mass, physical dimension, time of measurement, e
39、tc. The user should be aware that the use of a test portion that does not meet or exceed that specification could severely increase the contribution of the inhomogeneity of the CRM to the uncertainty of the certified property, to the point where the statistical parameters of certification are no lon
40、ger valid. The variation in the repeatability of different methods has another implication for the user. Since the degree of inhomogeneity of a CRM is dependent on the repeatability of the method of measurement, it is possible that a user, in applying a method capable of better repeatability, could
41、detect inhomogeneity in that CRM. In such cases, the observed inhomogeneity is already accounted for in the statistical parameters for the certified property and therefore the statistical tests presented in this Standard remain valid, but the scientific basis for using that particular CRM to give a
42、true assessment of the users method should again be questioned. It is well known that different methods of measurement of a property are not capable of equal repeatability. Accordingly there could arise instances where the user may wish to assess a method that has greater repeatability than that or
43、those used in the certification of the CRM. In such cases, the statistical tests presented in this Standard remain valid but the scientific basis for using that particular CRM to give a true assessment of the precision (and possibly the trueness) normally expected from the users method should be que
44、stioned. It is recommended that the user resorts to a CRM of lesser uncertainty, if available. For CRMs certified by a primary method, the user should not assume that his method is capable of matching the precision and trueness reported for the CRM. It is unreasonable therefore to apply the statisti
45、cal procedures in this Standard for assessing the trueness and precision of a method by application to a CRM using the certification parameters for a property reported in the certificate. The user, as a consequence, should either experimentally establish or make estimates based on available informat
46、ion for those parameters that are more appropriate. Similarly, where a user applies a method to a CRM that has been certified by a single different method, the user should not assume that the certification parameters for the certified property are applicable to his method except in cases where the t
47、rueness and precision capable by both methods are known to be comparable. PROTECTED BY COPYRIGHT Copyright Japanese Standards Association Provided by IHS under license with JSALicensee=IHS Employees/1111111001, User=Wing, Bernie Not for Resale, 03/16/2007 01:38:45 MDTNo reproduction or networking pe
48、rmitted without license from IHS -,-,- 3 Q 0033 : 2002 (IS0 Guide 33 : 2000) One of the important considerations in selecting a CRM for use, either in assessing the trueness and precision of a method or in the calibration of instruments in a method is the level of uncertainty required by the end-use of the method. Obviously the user should not apply a CRM of greater uncertainty than permitted by the end- use. The selection of CRMs should take into account not only the level of uncertainty required for the intended purpose but also their availability, cost, a