International agreements and decisions concerning trade and our social well-being increasingly require mutual recognition of measurements and tests among nations. The Mutual Recognition Arrangement (MRA) on national measurement standards and calibration and measurement certificates issued by NMIs rests upon the assumption of equivalence of national measurement standards in each country. In October 1999, the directors of NMIs for its original 38 member states of the Meter Convention and two international organizations signed the MRA; nearly 100 countries and associates now have signed the MRA. The MRA provides an open, transparent, and comprehensive framework for obtaining reliable quantitative information on the comparability of measurement services provided by the signatory NMIs.
Signatories to this MRA have the following responsibilities: (1) participate in relevant international comparisons, known as key comparisons, (2) participate in any relevant supplementary international comparisons of measurements, and (3) document the existence of a quality system and demonstrations of competence for its measurement services to customers. The expected outcome from these activities is to provide statements for each signatory of its calibration and measurement capabilities (CMCs) in a publically-available database. NIST has taken a leadership role in the CCQM and in the Chemical Metrology Working Group of the Interamerican System for Metrology (SIM) to assure the equitable and metrologically sound implementation of this MRA.
The CCQM currently has ten working groups: (1) Inorganic Analysis, (2) Electrochemical Analysis, (3) Gas Analysis, (4) Organic Analysis, (5) Surface Analysis (6) Protein Analysis, (7) Cell Analysis, (8) Nucleic acid Analysis, (9) Key Comparison and CMC Quality, and (10) Strategic Planning. These working groups are responsible for selecting and overseeing the operation of key comparisons, in which participating laboratories demonstrate their measurement or material preparation capabilities. Staff members of the Chemical Sciences Division (CSD) are involved in the various activities within several working groups. Since its inception over 20 years ago, over 150 key comparison studies and a similar number of pilot studies have been conducted under the auspices of the CCQM. CSD has participated in a large majority of these key comparisons, serving as the coordinating laboratory in nearly half of these key and pilot studies.