The LGC Standards catalogue 'Higher order reference materials' includes a special range of reference materials, mainly from national metrology institutes.
The term 'higher order' stems from the European directive on in vitro diagnostic (IVD) medical devices (directive 98/79/EC).
For example, the catalogue includes primary calibrators, which are materials used to calibrate reference measurement procedures.
Higher order reference materials are produced by institutes or international organisations with responsibility for metrological traceability.
The materials have been thoroughly characterised using the best available measurement procedures, sometimes as part of an interlaboratory comparison between national metrology institutes.
The uncertainty of material property values should, therefore, be the smallest attainable.
Higher order reference materials are primarily associated with clinical measurements.
A Joint Committee for Traceability in Laboratory Medicine (JCTLM) has been set up, one of its tasks being to identify higher order reference materials.
This catalogue has been checked against information provided by the JCTLM until July 2008.
It is, however, equally important to identify primary calibrators in other analytical fields.
Future editions of this catalogue may, therefore, list materials used to calibrate measurements in other fields.
All higher order reference materials are sold with detailed certificates of analysis, where in addition to the certified properties, their associated uncertainty and metrological traceability, instructions for storage, handling and use are also described.
Several producers, for example, the IRMM, provide a certification report on request.
This is a detailed report about manufacturing, quality control and certification procedures including the results from external organisations.
The production of higher order reference materials underpins the national and/or international measurement infrastructure.
The producers have a key role in developing, supporting and promoting good measurement practice.
The cost of production is partially covered by government or other funding and, therefore, the sales price does not fully represent the true cost of production, characterisation and certification.
