1、BS ISO8196-2:2009ICS 67.100.10NO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAWBRITISH STANDARDMilk Definitionand evaluation of theoverall accuracy ofalternative methods ofmilk analysisPart 2: Calibration and quality controlin the dairy laboratoryThis British Standardwas publish
2、ed underthe authority of theStandards Policy andStrategy Committee on 30November 2009. BSI 2009ISBN 978 0 580 58448 0Amendments/corrigenda issued since publicationDate CommentsBS ISO 8196-2:2009National forewordThis British Standard is the UK implementation of ISO 8196-2:2009.The UK participation in
3、 its preparation was entrusted to TechnicalCommittee AW/5, Chemical analysis of milk and milk products.A list of organizations represented on this committee can be obtained onrequest to its secretary.This publication does not purport to include all the necessary provisionsof a contract. Users are re
4、sponsible for its correct application.Compliance with a British Standard cannot confer immunityfrom legal obligations.BS ISO 8196-2:2009Reference numbersISO 8196-2:2009(E)IDF 128-2:2009(E)ISO and IDF 2009INTERNATIONAL STANDARD ISO8196-2IDF128-2Second edition2009-10-01Milk Definition and evaluation o
5、f the overall accuracy of alternative methods of milk analysis Part 2: Calibration and quality control in the dairy laboratory Lait Dfinition et valuation de la prcision globale des mthodes alternatives danalyse du lait Partie 2: Calibrage et contrle qualit dans les laboratoires laitiers BS ISO 8196
6、-2:2009ISO 8196-2:2009(E) IDF 128-2:2009(E) PDF disclaimer This PDF file may contain embedded typefaces. In accordance with Adobes licensing policy, this file may be printed or viewed but shall not be edited unless the typefaces which are embedded are licensed to and installed on the computer perfor
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9、ting to it is found, please inform the ISO Central Secretariat at the address given below. COPYRIGHT PROTECTED DOCUMENT ISO and IDF 2009 All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means, electronic or mechanical, i
10、ncluding photocopying and microfilm, without permission in writing from either ISO or IDF at the respective address below. ISO copyright office International Dairy Federation Case postale 56 CH-1211 Geneva 20 Diamant Building Boulevard Auguste Reyers 80 B-1030 Brussels Tel. + 41 22 749 01 11 Tel. +
11、32 2 733 98 88 Fax + 41 22 749 09 47 Fax + 32 2 733 04 13 E-mail copyrightiso.org E-mail infofil-idf.org Web www.iso.org Web www.fil-idf.org Published in Switzerland ii ISO and IDF 2009 All rights reservedBS ISO 8196-2:2009ISO 8196-2:2009(E) IDF 128-2:2009(E) ISO and IDF 2009 All rights reserved iii
12、Contents Page Foreword iv Foreword .v Introductionvi 1 Scope1 2 Normative references1 3 Terms, definitions, and symbols .1 3.1 Terms and definitions .1 3.2 Symbols2 4 Calibration of instruments3 4.1 General principles .3 4.2 General procedure.3 4.3 Frequency of calibration control .10 4.4 Centralize
13、d calibration11 5 Quality control in a routine dairy laboratory 11 5.1 Verification of repeatability 11 5.2 Daily check on short-term stability of the instrument .11 5.3 Verification of bias between laboratories .14 5.4 Verification of the difference between reference and alternative method results1
14、4 5.5 Verification of the compliance of alternative method results with a compositional requirement16 6 Examples18 6.1 Calculation of statistical values.18 6.2 Determination of repeatability20 6.3 Verification of the exactness of the calibration .20 6.4 Determination of accuracy .22 6.5 Checking the
15、 difference between reference and alternative method results .22 6.6 Conclusions .22 6.7 Verification of compliance with target values and upper or lower limits 23 Bibliography25 BS ISO 8196-2:2009ISO 8196-2:2009(E) IDF 128-2:2009(E) iv ISO and IDF 2009 All rights reservedForeword ISO (the Internati
16、onal Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The work of preparing International Standards is normally carried out through ISO technical committees. Each member body interested in a subject for which a technical committee has been
17、 established has the right to be represented on that committee. International organizations, governmental and non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standa
18、rdization. International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2. The main task of technical committees is to prepare International Standards. Draft International Standards adopted by the technical committees are circulated to the member bodies for
19、voting. Publication as an International Standard requires approval by at least 75 % of the member bodies casting a vote. Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. ISO shall not be held responsible for identifying any or all
20、such patent rights. ISO 8196-2|IDF 128-2 was prepared by Technical Committee ISO/TC 34, Food products, Subcommittee SC 5, Milk and milk products, and the International Dairy Federation (IDF). It is being published jointly by ISO and IDF. This second edition of ISO 8196-2|IDF 128-2 cancels and replac
21、es the first edition (ISO 8196-2:2000), which has been technically revised. ISO 8196|IDF 128 consists of the following parts, under the general title Milk Definition and evaluation of the overall accuracy of alternative methods of milk analysis: Part 1: Analytical attributes of alternative methods P
22、art 2: Calibration and quality control in the dairy laboratory Part 3: Protocol for the evaluation and validation of alternative quantitative methods of milk analysis BS ISO 8196-2:2009ISO 8196-2:2009(E) IDF 128-2:2009(E) ISO and IDF 2009 All rights reserved vForeword IDF (the International Dairy Fe
23、deration) is a non-profit organization representing the dairy sector worldwide. IDF membership comprises National Committees in every member country as well as regional dairy associations having signed a formal agreement on cooperation with IDF. All members of IDF have the right to be represented at
24、 the IDF Standing Committees carrying out the technical work. IDF collaborates with ISO in the development of standard methods of analysis and sampling for milk and milk products. The main task of Standing Committees is to prepare International Standards. Draft International Standards adopted by the
25、 Action Teams and Standing Committees are circulated to the National Committees for voting. Publication as an International Standard requires approval by at least 50 % of IDF National Committees casting a vote. Attention is drawn to the possibility that some of the elements of this document may be t
26、he subject of patent rights. IDF shall not be held responsible for identifying any or all such patent rights. ISO 8196-2|IDF 128-2 was prepared by the International Dairy Federation (IDF) and Technical Committee ISO/TC 34, Food products, Subcommittee SC 5, Milk and milk products. It is being publish
27、ed jointly by ISO and IDF. All work was carried out by the Joint IDF-ISO Action Team on Automated methods of the Standing Committee on Quality assurance, statistics of analytical data and sampling under the aegis of its project leader, Mr. O. Leray (FR). This edition of ISO 8196-2|IDF 128-2, togethe
28、r with ISO 8196-1|IDF 128-1 and ISO 8196-3|IDF 128-3, cancels and replaces IDF 128:1985, which has been technically revised. ISO 8196|IDF 128 consists of the following parts, under the general title Milk Definition and evaluation of the overall accuracy of alternative methods of milk analysis: Part
29、1: Analytical attributes of alternative methods Part 2: Calibration and quality control in the dairy laboratory Part 3: Protocol for the evaluation and validation of alternative quantitative methods of milk analysis BS ISO 8196-2:2009ISO 8196-2:2009(E) IDF 128-2:2009(E) vi ISO and IDF 2009 All right
30、s reservedIntroduction The main purpose of this part of ISO 8196|IDF 128 is to provide practical details and recommendations for the calibration of instruments and quality control in routine dairy laboratories, including the checking of compliance with a specification value or limit. ISO 8196-1|IDF
31、128-1 is mainly intended for users to assess alternative methods of analysis and gives guidance for routine laboratories using these methods. This part of ISO 8196|IDF 128 relates directly to ISO 8196-1|IDF 128-1 for the definition of the relevant performance characteristics, for the quantitative ev
32、aluation of the overall accuracy and the establishment of relevant standard limit values to comply with in analytical quality assurance as described. The general concepts apply to all analytical methods, but special emphasis is given to rapid physicochemical methods which are currently in use for th
33、e compositional testing of milk. ISO 8196|IDF 128 (all parts) only specifies the single linear regression model as a simplified approach to allow users to determine equivalence of an alternative method with a reference method. However, the linear regression approach is valid as a determination of me
34、thod equivalence only in limited circumstances or if a high correlation between the results of the reference method and the routine method is achieved. If a high correlation is not achieved, recourse should be made to other data handling and measurement error modelling techniques. Although these tec
35、hniques are referred to, they are not specified in ISO 8196|IDF 128 (all parts). BS ISO 8196-2:2009INTERNATIONAL STANDARD ISO 8196-2:2009(E)IDF 128-2:2009(E) ISO and IDF 2009 All rights reserved 1Milk Definition and evaluation of the overall accuracy of alternative methods of milk analysis Part 2: C
36、alibration and quality control in the dairy laboratory 1 Scope This part of ISO 8196|IDF 128 gives guidelines for the calibration of instruments and quality control procedures for milk analysis in dairy laboratories. 2 Normative references The following referenced documents are indispensable for the
37、 application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. ISO 8196-1|IDF 128-1:2009, Milk Definition and evaluation of the overall accuracy of alternative methods of m
38、ilk analysis ISO 8196-3|IDF 128-3:2009, Milk Definition and evaluation of the overall accuracy of alternative methods of milk analysis Part 3: Protocol for the evaluation and validation of alternative quantitative methods of milk analysis 3 Terms, definitions, and symbols 3.1 Terms and definitions F
39、or the purposes of this document, the terms and definitions given in ISO 8196-1|IDF 128-1 and the following apply. 3.1.1 standardization of an instrument experimental evaluation of the exactness of the calibration of an instrument by reference to the true values given either by a reference method or
40、 by standard materials or a standard instrument 3.1.2 calibration of an instrument adjustment of the signal from an instrument so that, at each level of the component, the mean of individual test results given by the instrument closely approximates the true value of the component concentration IMPOR
41、TANT Even if the term “calibration” is often used for both the standardization and calibration of instruments (see Clause 4), the use of these words according to the definitions in 3.1.1 and 3.1.2 is strongly recommended. BS ISO 8196-2:2009ISO 8196-2:2009(E) IDF 128-2:2009(E) 2 ISO and IDF 2009 All
42、rights reserved3.2 Symbols b linear regression coefficient or slope d average of differences dior mean bias didifference between means of duplicates of xiand yireld relative mean bias dL limit of the mean bias d reldL limit of the relative mean bias m0reference value for the control chart n number o
43、f replicates Pxysum of products of x and y q number of samples r repeatability limit rxycorrelation coefficient R reproducibility limit Sdsum of squares of d Sxsum of squares of x Sysum of squares of y sbstandard deviation of slope sx0standard error of estimate x0syestimate of standard deviation of
44、y syxestimate of the standard deviation of accuracy tobsobserved value of the Student t-test t1 /2t-value of the Student distribution for a two-sided probability 1 t1 t-value of the Student distribution for a one-sided probability 1 u1 /2value of the standard normal distribution for a two-sided prob
45、ability 1 x arithmetic average of ix ix mean of duplicates of xiy arithmetic average of iy iy mean of duplicates of yi()yx predicted values from x by linear regression. degree of freedom rstandard deviation of repeatability Rstandard deviation of reproducibility ystandard deviation of y yxstandard d
46、eviation of accuracy yxrelrelative standard deviation of accuracy BS ISO 8196-2:2009ISO 8196-2:2009(E) IDF 128-2:2009(E) ISO and IDF 2009 All rights reserved 34 Calibration of instruments 4.1 General principles This clause only considers the general principles of calibration which apply to any alter
47、native method of milk analysis. Detailed and specific instructions for the calibration procedure, as well as for the preliminary checks concerning each group of methods, shall be given in specific documentation. The calibration here described is based on the assumption of an existing linear relation
48、ship between the alternative method and the reference method. The utilization of an ordinary least-squares (OLS) linear regression model with the reference method as dependent variable (y-axis) is recommended as practical and reliable: a) the measured residual standard deviation is structurally the
49、lowest and is independent of the exactness of calibration, hence it can be used for calibration control as a method accuracy characteristic (see ISO 8196-1|IDF 128-1); b) prediction of true values from alternative method values and calculation of associated errors is simplified; c) the differences in measurement results as compared to applying other linear regression models are not significant. 4.2 General procedure 4.2.1 Preliminary checks 4.2.1.1 Instrument checks: all funct
