Traceability in chemical measurements for the end users

Traceability is the foundation of any metrological science. Traditionally t his term has been associated with the results of a particular measure as sy nonymous with the accuracy or reliability of such results (i.e., a certain level of quality). It ensures a clear( unbroken) relationship between resul ts and the corresponding samples by using appropriate standards and calibra ted equipment, This simple principle can be easily implemented in physical measurements, in which - commonly - the measurement process is mainly perfo rmed by the simple use of a (single) calibrated equipment. The case of chem ical measurements is quite different because only the measurement step of t he analytical process can be calibrated, but not the other steps, As measur ements have a clear sample dependence, standards are not available in many situations. Therefore, the term metrology in chemistry needs to relate to a wider meaning of traceability, more addressed to a practical approach whic h is useful for end users (chemists and clients). Some adaptations are need ed if a rational use of the term is to be applied to routine analytical wor k. In this article we propose a more practical and flexible view of term, ' traceability' in the field of metrology in chemistry. (C) 1999 Elsevier Sci ence B.V. All rights reserved.