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Afegeix-ho a l'agenda (iCal)
Dr. Rodrigo Caciano de Sena. National Institute of Standards, Quality and Technology (INMETRO), Brazil
The ability to perform accurate and reliable measurements is one the essential foundations of an advanced industrial society. The process of linking measurements to a unique primary standard or reference is known as traceability. Scientists and laboratory technicians know how complex is to ensure everyday measurements traceability. Now can you imagine how complex is to guarantee this on a global scale?
The basis for physical metrology was created towards the end of the 19th century to meets the needs of industrialization and global trade. This allowed establishing a cohesive worldwide traceability system for physical measurements. Only at the end of the 20th was adopted a global chemical metrology system, but its implementation was not trivial. When compared to physical metrology, chemistry has an intrinsic characteristic: there are many thousands of chemical substances that are measured in very complex matrices or at minute concentrations. These measurements require complicated procedures involving steps such as extractions or separation of the analytes. Traceable calibration standards alone are not able to ensure consistency among measurements. To ensure the comparability is a global scale the Bureau International des Poids et Mesures (BIPM) created the Consultative Committee for Metrology in Chemistry (CCMQ) that works organizing high level measurements comparisons between their members and collaborate on new measurement capabilities. The comparisons are very similar to a proficiency testing but the main objective is to perform measurements with much smaller uncertainty and in general the dispersion of results is minimum. Achieving this is only possible because the National Institutes of Metrology (NMI) maintain a complex infrastructure and when possible use primary methods. Using this approach, the CCQM members are working to demonstrate global consistency not only for calibration standards but also for complex matrices.
The National Institute of Standards, Quality and Technology (INMETRO) has worked in Brazil aiming to create an infrastructure to underpin the traceability in chemical measurements. During the lasted two decades were developed and implemented primary methods, production and certification of reference materials (contaminants in water, soil, milk, etc) and, organizing proficiency testing schemes.