ISO 33405-2024 PDF

Full title and description

ISO 33405:2024 — Reference materials — Approaches for characterization and assessment of homogeneity and stability. This International Standard provides concepts and practical approaches for assessing the homogeneity and stability of reference materials (RMs), for their characterization and value assignment, for evaluating uncertainty of certified values, and for establishing metrological traceability of those values.

Abstract

The document explains methods to assess RM homogeneity and stability, risk management for stability-related issues, procedures for characterization and value assignment, evaluation of uncertainty for certified values, and establishing traceability. It gives brief guidance on commutability assessment and qualitative properties but does not provide detailed statistical methods for qualitative or multivariate quantities. The guidance supports implementation of ISO 17034.

General information

• Status: Published
• Publication date: 3 May 2024
• Publisher: International Organization for Standardization (ISO)
• ICS / categories: 71.040.30 (Chemical reagents)
• Edition / version: Edition 1 (2024)
• Number of pages: 98 (ISO edition)

Scope

This Standard specifies approaches and guidance for the production and assessment of reference materials, focussing on: designing and carrying out homogeneity studies; planning and performing stability studies including risk assessment for property degradation; strategies for characterization and value assignment; estimation of uncertainties associated with certified values; and establishing metrological traceability. It supports (and is intended to be used alongside) ISO 17034. It is not intended for multivariate quantities (for example, complex spectral data) and does not fully develop statistical methods for qualitative properties.

Key topics and requirements

• Principles and terminology for homogeneity and stability assessment.
• Design of sampling and experimental plans for homogeneity testing (including sample selection and sub-sampling considerations).
• Stability study design, accelerated and real-time approaches, and risk management for property changes.
• Approaches to characterization and value assignment for properties of interest.
• Evaluation and reporting of uncertainty for certified values.
• Establishment and documentation of metrological traceability for assigned values.
• Brief guidance on commutability assessment and on qualitative property considerations (with limits noted).

Typical use and users

Primary users are producers of reference materials and certified reference materials (CRMs), national metrology institutes, conformity assessment bodies and accreditation assessors, analytical laboratories that develop or use RMs for quality control and calibration, and regulators or quality managers involved in measurement assurance. The Standard is used when planning RM production, designing homogeneity and stability studies, assigning values and reporting uncertainties.

Related standards

Closely related documents include ISO 17034 (General requirements for the competence of reference material producers), national adoptions (for example BS ISO 33405), and other ISO 334xx series documents (such as ISO 33403 on RM use and recommendations). ISO Guide 35:2017 is shown in the historical lifecycle as previously withdrawn in the context of this suite of documents. These related standards are used together for RM production, certification and use.

Keywords

reference material; certified reference material; homogeneity; stability; characterization; value assignment; uncertainty evaluation; metrological traceability; commutability; ISO 17034.

FAQ

Q: What is this standard?

A: ISO 33405:2024 is an international standard that provides approaches and guidance for characterizing and assessing the homogeneity and stability of reference materials, and for related characterization, uncertainty evaluation and traceability activities.

Q: What does it cover?

A: It covers planning and performing homogeneity and stability studies, risk management for stability, methods for characterization and value assignment, evaluation of uncertainty for certified values, and establishing metrological traceability. It gives brief guidance on commutability and qualitative properties but excludes detailed statistical methods for qualitative or multivariate quantities.

Q: Who typically uses it?

A: Producers of RMs/CRMs, accreditation bodies, analytical laboratories, national metrology institutes, and quality managers involved in measurement assurance and RM use.

Q: Is it current or superseded?

A: ISO 33405:2024 is a current, published International Standard (first edition, published May 2024). It supersedes/replaces earlier guidance material in the lifecycle context (ISO Guide 35:2017 is shown as previously withdrawn in relation to this suite of documents).

Q: Is it part of a series?

A: Yes — it is part of a set of documents addressing reference materials and their use (the ISO 334xx family) and is intended to be used alongside ISO 17034 and related ISO documents covering production, certificates and use of RMs.

Q: What are the key keywords?

A: Reference material, certified reference material, homogeneity, stability, characterization, uncertainty, traceability, commutability, RM producer, ISO 17034.