Use of reference materials

Why use reference materials? Answering this question is the main objective of this article.

Three main categories of reasons can be quickly identified:

• to perform necessary calibrations and demonstrate traceability to the International System of Units (SI); to make two measurement results comparable;

• to validate one method or verify another;

• to monitor measurement processes

Within the framework of standards governing conformity assessment activities, reference materials play an essential role whenever it is necessary to ensure metrological traceability to the SI. They are specifically mentioned in several normative standards, such as ISO/IEC 17020 (§ 6.2.10 and § 6.3.2 in its 2026 revision), ISO/IEC 17025 (§ 6.5.2 and 6.5.3), and ISO 15189 (§ 6.2.10).

These standards also specify that reference materials may be used to meet requirements related to method validation and verification, as well as to the monitoring of measurement processes, particularly to ensure the validity of analytical results (e.g., ISO/IEC 17025 § 7.7).

The use of reference materials in the context of method validation or verification makes it possible, in particular, to assess the accuracy of a method, to verify the absence of undesirable matrix effects, or to demonstrate that the results obtained are consistent with a known reference value.

Today, SI units are no longer defined by physical objects, but by fundamental constants of nature, whose numerical values have been precisely established. However, in the day-to-day practice of laboratories and conformity assessment bodies, it remains necessary to have operational realizations of these units, whether they be the volt, the kilogram, the meter, the pascal, the liter, etc. In certain fields, this realization can only be achieved through reference materials, particularly when expressing quantities such as concentrations (for example, in mol·L ^–1 ).

The objective of this article is to provide the clearest possible understanding of the key principles related to reference materials, as well as the various uses of reference materials in conformity assessment activities, all without delving into excessive complexity, in order to facilitate an informed dialogue with auditors and support internal decision-making. It is intended for professionals in analytical, testing, calibration, or inspection laboratories, as well as quality managers or those responsible for the control of measuring equipment, who are involved in the use of reference materials as part of an accreditation process...