Environmental and biochemical trace-metal speciation studies by radiotracers and neutron activation analysis.

Although knowledge of the total concentrations of trace metals in the environment and living organisms is still the essential starting point for any toxicological evaluation, it is, however, not sufficient to explain the mechanisms responsible for retention and toxic effect of trace metals. Differentiation between their chemical and biochemical forms is necessary. The need to resolve the total concentration of trace metals into single chemical species poses great experimental difficulties and imposes the use of very sensitive analytical techniques for trace metal determinations after specific preseparation procedures of the different chemical species.Thus, once the chemical or biochemical metal species have been selectively isolated, the speciation becomes merely an analytical problem, which requires high sensitivity and accuracy, as well as the evaluation of matrix effects, blanks, contamination, loss, and sampling.This paper describes the use of nuclear and radiochemical techniques related to chemical and biochemical speciation problems at the Joint Research Centre, Ispra, with carrier-free radiotracers and radiochemical neutron activation analysis.