**2. Applications of atomic absorption spectroscopy in medicine**

Atomic absorption spectroscopy is a sensitive means for the quantification of some 70 elements and is of use in the analysis of biological samples (Skoog & West, 1984). FAAS allows the detection of Ag, Al, Au, Cd, Cu, Hg, Pb, Te, Sb and Sn with great sensitivity (Taylor et al., 2002). For most elements, the EAAS has lower detection limits than the FAAS. The incorporation of the new technology in the Laboratory of Clinical Biochemistry opened the possibility of approaches which had been unthinkable until then. For many of them it meant a reinforcement in the central position they held in hospital research. For those which incorporated spectroscopy it meant the possibility of new diagnostic, therapeutic and toxic controls.

In this chapter, a series of research studies are presented as example of the above mentioned. Thus, with respect to the Sr, refer to section 2.1, the first paper deals with the discrimination factor between Ca/Sr in absorption intestinal mechanisms. Afterwards, the different behavior of these metals in the binding to serum proteins is studied. And finally, the possibility of a hormonal regulation mechanism of serum levels of this element is evaluated, given the similarity of its biological behavior with the Ca.

The quantification of element bound to protein derived towards the direct applications for the study of medical problems such as the distribution of Zn in the acute and chronic overload and de Zn and Cu in the serum proteins in myocardial infarction.

Later, in section 2.2, a specific problem resulting from industrial development among other causes, threatening a part of the population –Pb poisoning– was tackled, analysing the serum and urine concentration of Pb and the hem biomarkers. This example is particularly useful not only because of what the technology meant for the diagnosis and control of this disorder but also because it has allowed to observe how the levels of this element in our city and, in general, in the West has declined over the years.

Finally, in section 2.3, an actual research is included: the design of a new strategy or approach possibility in the knowledge of the physiopathology of different neurological conditions based on the concentration of certain trace elements in the CSF, as well as of other parameters such as the cellularity, the proteins concentration, etc.

#### **2.1 Strontium**

This first group of papers serves as a model to analyze how this new technique allows evolving from the specific research problems (intestinal absorption, transport of element bound to proteins, etc.) to applications in medical pathology, such as the binding of Zn and Cu to plasma proteins after myocardial infarction.
