Trends in certified reference materials for the speciation of trace elements

The measurement of the chemical species of elements (instead of the total e lement concentration) has become an irreversible trend in analytical chemis try. The motivation lies in the fact that the biochemical and geochemical b ehaviour of an element is governed by its species. Quality assurance of the analytical procedures used for speciation analysis requires the analysis o f representative reference materials, certified for the relevant species. U p to now the number of existing certified reference materials for trace ele ment species is very limited. The most important ones are environmental CRM s certified for trialkyltin compounds, methylmercury, Cr(III)/Cr(VI) and fo od CRMs certified for arsenic species and methylmercury. Major developments are to be expected in CRMs focussed on environmental problems, including w aste treatment, on bioavailability of trace elements in food and on bio-mon itoring in occupational health and hygiene. It is, however, unlikely that t he producers of CRMs will ever be able to cover all needs. Add to this that many, very active species are notoriously unstable and/or short living and require in-situ analysis. This will lead to different analytical developme nts, such as analyses in-situ, where the classical concept of CRh?s may not stand firm anymore.