What are reference materials used for

Reference materials are used for a range of functions within measurement processes, including:

• Calibration, i.e. the establishment of a relation between a 'signal' and the quantity intended to be measured. In the simple case, a calibration factor and its uncertainty are calculated from the ratio of the observed and certified values.

   

• Method development and validation, i.e. to check if the observed value measured on the reference material and the certified value match within the uncertainty (trueness control).

• Establishment of metrological traceability, i.e. to ensure that results are traceable to stated references and are comparable to other results.

• Quality control purposes, for example:
  -- to control the accuracy of a single measurement within the stated uncertainty,
  -- to check for long-term stability of an analytical procedure and laboratory performance (establishment of control charts),
  -- proficiency testing, either with non-certified RMs or when the certified reference value of the material is used as the assigned value for the PT round.

   

• Estimation of measurement uncertainty.

   

It has to be considered that a single reference material cannot be used for both calibration and validation of results in the same measurement procedure.

For additional information see:

[1] ISO-Guide 32 (1997) Calibration of chemical analysis and use of certified reference materials

[2] ISO-Guide 33 (2000) Uses of certified reference materials

[3] EURACHEM-Guide (2002) The selection and use of reference materials - a basic guide for laboratories and accreditation bodies (identical to ILAC G9 (2005))

(http://www.ilac.org/documents/ILAC_G9_2005_guidelines_for_the

_selection_and_use_of_reference_material.pdf)

[4] ERM application note 3 Using reference materials to establish traceability

(http://www.erm-crm.org/html/ERM_products/application_notes/application_note_3/ERM
_application_note_3_-_Mar08__4_.pdf)

[5] ISO 16042:2007 Iron ores – Guidelines for the use of certified reference materials

[6] M. Thompson, S.L.R. Ellison, A. Fajgelj, P. Willetts, R. Wood; Harmonised guidelines for the use of recovery information in analytical measurement. Pure & Appl. Chem. (1999) 71: 337–348

[7] V. Barwick, S. Burke, R. Lawn, P. Roper and R. Walker; Applications of Reference Materials in Analytical Chemistry. Royal Society of Chemistry, 2001, ISBN 0-85404-448-5

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