Technical ISO Report ISO/TR 33402 First edition Good practice in reference material 2025-01 preparation Bonne pratique pour la preparation des matériaux de réference Reference number ISO/TR 33402:2025(en) @ ISO 2025 IS0/TR 33402:2025(en) COPYRIGHT PROTECTED DOCUMENT @ IS0 2025 All rights reserved. Unless otherwise specified, or required in the context of its implementation, 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 copyright office CP 401 · Ch. de Blandonnet 8 CH-1214 Vernier, Geneva Phone: +41 22 749 01 11 Email: [email protected] Website: www.iso.org Published in Switzerland @ IS0 2025 - All rights reserved ii IS0/TR 33402:2025(en) Contents Page .iv Foreword. Introduction Scope. 1 1 2 Normative references 1 3 Terms and definitions 4 Overview of preparation of candidate reference materials (RMs) 1 5 Material specification. 2 5.1 2 General. 5.2 Matrix type and matching 2 5.3 Properties and property values 3 5.4 Unit size, 3 5.5 Total bulk amount of material. 3 6 Sourcing and selection of bulk material 3 Material processing 7 4 7.1 General 7.2 Avoidance of contamination 4 Drying 7.3 4 7.4 Milling and grinding. 5 7.5 Sieving. 5 7.6 Mixing and blending 7.7 Filtration 5 7.8 Stabilization 7.9 Sterilization 6 Subdivision and packaging. 7.10 6 7.10.1 General 7.10.2 Choice of containers 6 7.11 Subdivision procedures. Annex A (informative) Case study 1 - Production of a quality control material (QcM) from coal. Annex B (informative) Case study 2 Production of geological or metallurgical quality control materials (QCMs) 11 Annex C (informative) Case study 3 - Production of a wheat flour fortified with folic acid quality control material (QCM). 18 .24 Annex D (informative) Case study 4 Bauxite quality control material (QCM) Annex E (informative) Case study 5 - Pharmaceutical reference standards. .29 Annex F (informative) Case study 6 - Production of testing materials for “bromate in water" .34 Bibliography. 40 @ IS0 2025 - All rights reserved iii IS0/TR 33402:2025(en) Foreword Iso (the International 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 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/lEC Directives, Part 1. In particular, the different approval criteria needed for the different types of IsO document 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 informat