Storage of reference materials is essential for preserving the integrity of the samples. Stability studies for storage and transport are an integral part of any reference material production cycle. Based on these studies, the appropriate storage and transport conditions for each material are defined.
IRMM inaugurated its state-of-the-art storage facilities for reference materials in 2004. Rooms for storage of reference materials at 18 °C (270 m2), 4 °C (120 m2), -20 °C (200 m2), -40 °C (100 m2) are available as are facilities for storage at -70 °C and -150 °C (above liquid nitrogen), in addition to dedicated rooms for highly flammable materials. Reference materials and finished candidate reference materials are strictly separated from raw materials (which are stored in separate rooms) to avoid cross-contamination. Sufficient redundancy is available to allow quick shifting of samples in case of emergencies. These buildings currently contain roughly 500 000 samples of more than 700 different materials.
Storage conditions in all facilities of course monitored on a 24 h/24 h basis and IRMM's five authorised distributors are contractually obliged to meet the same specifications (and to regularly report the temperature readings) for their consignment stock. In this way IRMM can ensure that materials stored at its own and at its authorised distributor's premises are stored in the same conditions as at IRMM. Stability testing of the materials in regular, predefined time intervals ensures stability of CRMs over their entire lifetime.