Total indices in analytical sciences

This article outlines the state of the art and the prospects for total indices, which are measurands describing a group of (bio)chemical compounds possessing a similar nature/structure and/or exhibiting a similar function. it discusses various practical aspects, including: their main types, characteristics and requirements; the standards involved in their production; and, their forms of expression. Although this type of analytical method is widely used in environmental, food, clinical and industrial analysis, no systematic approach to its use has been developed to date, despite the pressing need to clarify the topic and to provide the required metrological and practical support. (C) 2003 Published by Elsevier B.V.