BEYOND TOTAL ELEMENT ANALYSIS OF BIOLOGICAL-SYSTEMS WITH ATOMIC SPECTROMETRIC TECHNIQUES

One of the fundamental limitations of atomic methods in biological ana lysis is their inability to distinguish individual physico-chemical fo rms of the metal. After a brief overview of 'hot' trace elements and a tomic techniques used for total element analysis in bioanalytical work , the importance and main challenges of speciation of toxic metals in biological systems is addressed. The main analytical problems of speci ation and present techniques/analytical strategies to tackle this prob lem are highlighted. Recent work on metal speciation in our laboratory is described in order to show that analytical difficulty is dependent on the chemical nature of the sought species (i.e., moving from 'stab le/kinetically inert' to 'unstable/fast reacting' species determinatio ns). New analytical strategies for more stable species (e.g., methylme rcury) by coupling a powerful separation technique with specific (atom ic) detectors are described. The concept and analytical application of non-chromatographic and vesicles-mediated HPLC-volatile species gener ation-atomic detection to the speciation of toxic species of Hg, As or Sn is discussed. It is emphasized that the complexity of toxic metal speciation in biological matrices calls for a 'several-complementary' analytical strategies approach. This concept of applying different-pri nciple-based separation units (e.g., ultramicrofiltration, FI or HPLC columns with different adequate packings) coupled with complementary d etectors (usually atomic ones) for tackling complex problems is stress ed. Comparative studies on the speciation of aluminium and silicon in human serum carried out in the author's laboratory are used throughout to illustrate this important point. Finally, some clinically relevant conclusions derived from such trace metal speciation research are hig hlighted.