Inorganic certified reference materials in 'water' - What do we have, what do we need?

An inventory was prepared of the Certified Reference Materials (CRMs) available on the international market for the matrix 'water', There are different types or classes of water available, ranging from artificial (distilled, lyophilised) to more natural origin (rain-, river, lake, estuarine, sea-water). Determinants covering both major and trace elements for each water class are summarised, The lists may suggest that most determinants/matrices have been made available through the various suppliers of CRMs, However, on looking at the reality of everyday analytical performance in many routine water-testing laboratories, the quality assurance of the analysis of a surprisingly large number of compounds is not supported by the availability of dedicated CRMs, That these are not necessarily obscure determinants is illustrated using examples from the field of environmental freshwater monitoring practices, and from certain aspects of climate research analyses in the marine environment. It is concluded that there is a need for an exchange of information on the needs between the producers of CRMs and the routine analysts. This may lead to the availability, and the common use, of CRMs that support the quality assurance of day-to-day routine analyses of water.