Certified Reference Materials (CRMs), produced by VKI, are designed to provide appropriate homogenous stable reference materials for quality control of environmental analyses. Certification is carried out in accordance with ISO Guide 30, 31, 33, 34, 35, ISO 5725 and ISO/REMCO N 37. All CRMs are traceable to a National Standard, or verified by a group of internationally recognised laboratories, and come with a Certificate of Analysis which states the certified value and the uncertainty at a stated level of confidence.

• Liquid references supplied in packs of glass ampoules ready for easy dilution