reference material

Reference materials with or without assigned quantity values can be used for measurement precision control whereas only reference materials with assigned quantity values can be used for calibration or measurement trueness control.

In a given measurement, a given reference material can only be used for either calibration or quality assurance.

Reference material comprises materials embodying quantities as well as nominal properties. Examplesof reference materials embodying quantities: EXAMPLE 1

Water of stated purity, the dynamic viscosity of which is used to calibrate viscometers.

A reference material is sometimes incorporated into an IVD medical device:EXAMPLE 1

Substance of known triple-point in a triple-point cell.

A reference material, accompanied by documentation issued by an authoritative body and referring to valid procedures used to obtain a specified property value with associated uncertainty and traceability, is called a certified reference material.EXAMPLE

Human serum with assigned quantity value for the cholesterol concentration and associated measurement uncertainty, used as a calibrator or measurement trueness control material.

Some reference materials have quantities that are metrologically traceable to a measurement unit outside a system of units. Such materials include measurement standards of biological origin to which International Units (IU) have been assigned by the World Health Organization.

The specifications of a reference material include its material traceability, indicating its origin and processing. Requirements for the specifications of reference materials for IVD medical devices are described in ISO 15194^[12].

Uses of reference materials can include the calibration of a measurement system, assessment of a measurement procedure, assigning values to other materials, and quality control. See also measurement standard (A.3.33).

Examination of a nominal property provides a nominal property value and associated uncertainty. This uncertainty is not a measurement uncertainty.

ISO/REMCO (Committee on reference materials) has an analogous definition but uses the term measurement process to mean examination (3.16), to cover both measurement and examination of a nominal property.