Reference materials play a critical role in quality assurance and contribute to the process of establishing traceability of units used to report laboratory results. The use of appropriate reference materials is an important aspect of accreditation to ISO/IEC 17025.

NMI's Chemical Reference Materials Facility identifies, produces and characterises reference materials that meet Australia’s measurement needs, responding to both national and international concerns (see NMI 28 Chemical Reference Materials). Our facility complies with ISO Guide 34 (2000) General Requirements for the Competence of Reference Material Producers and is certified by NATA for the production of certified reference materials (CRMs) and reference materials of pure substance organic solids at room temperature for chemical, sports, forensic, therapeutic and veterinary applications. Click here for details of our NATA accreditation.

NMI produces:

• a range of CRMs that are available for purchase for the detection and quantification of:
  • anabolic steroids (sport drugs) – catalogue and price list 
  • WADA-funded anabolic steroids (sport drugs) – catalogue and price list
  • forensic drugs – catalogue and price list
  • agrichemical and veterinary drugs – catalogue and price list
• certified matrix reference materials which we characterise using high-accuracy primary methods, such as isotope-dilution mass spectrometry, in order to produce reference values with small uncertainties which are traceable to SI
• materials prepared and characterised for our proficiency testing program are also sometimes made available to the Australian measurement community for use as reference materials – also see NMI 27 Proficiency Testing Schemes for Chemical Analysis

Click here for details of our reference gas mixtures and see below for more information on CRMs, matrix reference materials, selecting reference materials and COMAR, a free internet-based information service which helps testing and analytical laboratories to find the reference materials they need.

For further information contact chemref@measurement.gov.au.

Certified Reference Materials

The highest level measurement benchmarks are provided by CRMs. CRMs are a specific class of reference material whose property values (purity, concentration etc) are established and certified in accordance with metrological principles using established, international best practice protocols. CRMs can be pure chemical substances, blends or synthetic mixtures, and spiked or naturally occurring matrices.

CRMs are used to calibrate the measurement process and they all have common characteristics:

• assigned values are accompanied by an uncertainty statement
• information is given on the methods used to assign values
• the intended use of the CRM is described
• the reported values of CRMs are, by definition, traceable to accurate realisations of the units in which they are expressed

Appropriate use of CRMs will help you to assess the accuracy of your analysis and to establish the traceability of test results to national or international standards.

The following criteria apply to NMI's CRMs:

• compound identity is confirmed by a minimum of two spectroscopic techniques including NMR (¹H, ¹³C), GC–MS, LC–MS and FT–IR
• purity is assessed using a minimum of two techniques including GC–FID, HPLC, TGA, DSC, quantitative 1H NMR and elemental microanalysis
• the characterisation data for each compound are assessed by an independent scientific review panel as the final step in the certification process
• a comprehensive analytical report is provided with each compound and full details of chromatographic and spectral data are available on request

Matrix Reference Materials

Matrix reference materials are most valuable in the validation of analytical methods. Here their primary role is to calibrate the mass-transfer process. However they are also important:

• as quality control tools for assuring the ongoing performance of test methods and the validity of associated test results
• as a benchmark for comparing measurements made between different laboratories

Selecting Reference Materials

A large number of reference materials are available world-wide, not all of which are certified. The degree to which these materials are characterised and the detail of information provided to the purchaser are highly variable. The purchaser is responsible for choosing the most appropriate reference materials for a given purpose. This involves sourcing a reference material that best matches the analyte, application and matrix. Availability and price also need to be considered.

Key questions to ask are:

• How extensively characterised does the reference material need to be for this purpose?
• Will the uncertainty in the assigned values of the reference material contribute significantly to the overall uncertainty of your method?
• What level of traceability is required for your test results?

Purchasers can use COMAR to source reference materials.

COMAR is a free internet-based information service which helps testing and analytical laboratories to find the reference materials they need. The website is continually updated and currently it contains information on nearly 11,000 reference materials from about 250 producers in about 25 countries.

NMI is the Australian coding centre for COMAR and we are currently entering our own reference materials into COMAR. So far we have listed 110 NMI reference materials. If Australian reference materials producers wish to have their products listed on COMAR, contact chemref@measurement.gov.au.

Note:
NMI provides the link to COMAR as a service to Australian users. However, purchasers are urged to establish the suitability and quality of the reference materials cited in COMAR by direct enquiry with the providers. NMI does not warrant the quality of materials referenced in COMAR unless they have been prepared by NMI.