At the National Physical Laboratory (NPL), our Standard Reference Materials (SRMs) are produced in batches by external manufacturers who follow NPL’s agreed batch-manufacturing protocols. These protocols ensure consistency and use cylinders that are similar to those used for our Primary Reference Materials (PRMs).
Once produced, the mixtures are certified against NPL’s in-house PRMs. We then issue certificates that confirm the composition based on this analysis.
This method of manufacturing enables NPL to stock reference materials that satisfy the most commonly requested compositions, using economies of scale to reduce the cost, while maintaining suitable levels of uncertainty and good stability.
We are currently running an initial trial of 50 µmol mol⁻¹ nitrogen monoxide in nitrogen. If the trial is successful, we plan to expand the range of SRMs to include a wider range of compounds.
SRM