International ISO Standard IS033403 Reference materials - First edition Requirements and 2024-06 recommendations for use Materiaux de réference - Exigences et recommandations pour I'utilisation Reference number IS0 33403:2024(en) @ ISO 2024 IS02024 All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may 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 copyright office CP 40i : Ch. de Blandonnet 8 CH-1214 Vernier, Geneva Phone: +41 22 749 01 11 Email: [email protected] Website: www.iso.org Publishedin Switzerland @IS0 2024 - All rights reserved ii Contents Page Foreword. ..iv Introduction 1 Scope. .1 2 Normative references .1 & Terms and definitions .1 4 Symbols. .2 5 Conventions .2 6 RMs and their role in measurement .3 6.1 Common applications of RMs ..3 6.2 Property values. .5 6.2.1 General ..5 6.2.2Specification ofthe property. ..5 6.3 Uncertainty statement. ..6 6.4 Traceability statement. ..7 7 Handling of RMs and CRMs .8 8 Assessment of precision 8.1 General. ..8 8.2 Number of replicate measurements .9 8.3 Requirements with respect to the RM ..9 8.4 Measurement .10 8.5 Data treatment .10 8.6 Calculation and assessment of precision .11 9 Bias assessment .11 9.1 General. .11 9.2 Approach to bias checking .12 9.3 Utilizing bias data. 12 10 Calibration. .13 10.1 General 13 10.2 Practical considerations for calibration .13 10.3 Calibration models ..14 11 Assigning values to other materials .14 11.1 General .14 11.2 Pure substances.. .15 11.3 Preparation of calibrants ..16 12 Conventional scales. .16 13 Selection of RMs and CRMs .18 13.1 General .18 13.2 Selection of a CRM .18 13.3 Selection of RMs. .19 13.4 Relevance to the measurement system 20 Annex A (informative) Calibration models and associated uncertainty models .21 Annex B (informative) Decision errors ..24 Annex C (informative) Example of conventional scales .25 Bibliography .26 @ IS0 2024 - All rights reserved iii Foreword Iso (the International Organization for Standardization) is a worldwide federation of national standards bodies (isOmemberbodies).TheworkofpreparingInternationalStandards isnormallycarried outthrough Isotechnicalcommittees.Eachmemberbodyinterestedinasubjectforwhichatechnicalcommittee has been 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 standardization. The procedures used to develop this document and those intended for its further maintenance are described in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the different types of Iso documents should be noted. This document was drafted in accordance with the editorial rules of the ISo/IEC Directives, Part 2 (see www.iso.org/directives). Iso draws attention to the possibility that the implementation of this document may involve the use of (a) patent(s). Iso takes no position concerning the evidence, validity or applicability of any claimed patent rights in respect thereof. As of the date of publication of this document, Iso had not received notice of (a) patent(s) which may be required to implement this document. However, implementers are cautioned that this may not represent the latest information, which may be obtained from the patent database available at www.iso.org/patents. IsO shall not be held responsible for identifying any or all such patent rights. Any trade name used in this document is information given for the convenience of users and does not constituteanendorsement. For an explanation of the voluntary nature of standards, the meaning of Iso specific terms and expressions related to conformity