Isotope dilution technique for quantitative analysis of endogenous trace element species in biological systems

The recent developments and trends in quantitative speciation analysis of endogenous trace element compounds in biological systems by ICP isotope dilution MS are discussed. The use of two different isotope dilution techniques is critically evaluated with respect to their advantages and limitations: species-unspecific isotope dilution for the quantification of trace elements bound to unknown biomolecules and species-specific isotope dilution for the quantification of well-defined compounds. Recent data on the quantification of metallobiomolecules by isotope dilution analysis are summarized and future directions in this new field of analytical chemistry are highlighted.