ISO INTERNATIONAL STANDARD 13843 First edition 2017-06 Water quality Requirements for establishing performance characteristics of quantitative microbiological methods Qualité de I'eau-Exigences pour I'etablissement des caractéristiqes de performance des meéthodes microbiologiques quantitatives Reference number IS0 13843:2017(E) rso International Organization for Standardization HEJIANG INSTOFSTANDARDIZATIONC15956617 @IS02017 IS0 13843:2017(E) COPYRIGHTPROTECTEDDOCUMENT IS02017,PublishedinSwitzerland All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address below or ISO's member body in the country of the requester. ISO copyrightoffice Ch. de Blandonnet 8 . CP 401 CH-1214 Vernier, Geneva, Switzerland Tel. +41 22 749 01 11 Fax +41 22 749 09 47 copyright@iso.org www.iso.org PrganizationforStandardization icensee-ZHEJIANG INST.OF STANDARDIZRoISQ s1.7 - All rights reserved Not for Resale, 2017/9/11 05:55:55 etworking permitted without license from IHS IS0 13843:2017(E) Contents Page Foreword ..V Introduction. ...vi 1 Scope.. 2 Normative references 3 Terms and definitions ..1 4 Basic concepts 4.1 General .6 4.2 Characterization 4.3 Verification. ..8 4.4 Method comparison. 4.5 Samples .9 5 Specifications: some guideline values ..9 6 Designs for determining performance characteristics of a method ..10 6.1 General considerations.. ..10 6.2 Determination of sensitivity, specificity, efficiency, selectivity, false positive rate and false negative rate. ..10 6.2.1 Type of samples to be used ..10 6.2.2 Number of samples.. ..11 6.2.3 Procedure. .11 6.2.4 Categorical performance characteristics .11 6.2.5 Worked example. .12 6.3 Determination of the upper limit and consideration of the lower limit of detection ..14 6.3.1 Working range. 6.3.2 Upper limit related to linearity. ..14 6.3.3 Type and number of samples to be used ..14 6.3.4 Worked example. .15 6.3.5 The lower limit of detection ..16 6.4 Assessment of precision: Determination of repeatability and reproducibility ..16 6.4.1 General ..16 6.4.2 Repeatability .17 6.4.3 Intralaboratory reproducibility .18 6.5 Robustness 20 6.5.1 General 20 6.5.2 Experimental designs for effects due to time and temperature 20 6.6 Relative recovery 21 6.6.1 General. .21 6.6.2 Determination of relative recovery .21 6.7 Uncertainty of counting. .22 6.7.1 General 22 6.7.2 Experimental design for assessing the uncertainty of counting colonies .22 6.7.3 Example of individual (or personal) uncertainty of counting colonies.. 22 6.7.4 Example of intralaboratory uncertainty of counting colonies .23 6.7.5 Example of intralaboratory uncertainty of reading MPN ..23 7 Designs for single laboratory verification of a method ..24 7.1 General considerations. .24 7.2 Calculation of sensitivity, specificity, efficiency, selectivity, false positive rate and false negative rate. .24 7.2.1 Type of sample to be used .24 7.2.2 Number of samples.. .25 7.2.3 Procedure for confirmation .25 7.2.4 Categorical performance characteristics. .25 7.3 Determination of repeatability 26 Intematinal oganzation @stS2017 - All rights reserved iii ISee=ZHEJIANG INST OF STANDARDIZATION C1 5956617 cense with ISO ed without license from IHS Not for Resale, 2017/9/11 05:55:55