chapter  4
Atomic Spectrometry in Clinical and Biological Analysis
ByAndrew Taylor
Pages 16

Within biological systems, elements may be classied as those essential to the well-being of the organism and those that have no known or demonstrable function and are therefore regarded as nonessential.1,2 On the basis of the usual concentrations within tissues and body uids, they may also be classied as major or trace elements, trace elements being dened as those that individually contribute no more than 0.01% of the dry body mass.3 All the major elements and a limited number of trace elements are essential (Table 4.1); all others that may be detected are nonessential. Essential elements are required for various biological functions,1 for example,

• Enzyme structure and function • Hormone structure and function • Vitamin structure and function (e.g., B12) • Transport of oxygen • Structure of macromolecules

When any are present in less than optimal concentrations, symptoms of morbidity will be evidentindeed, the severity of deciency may be such that death is the eventual outcome (Figure 4.1). At the same time, all elements, whether essential or nonessential, are toxic if they accumulate in tissues to suf-ciently large concentrations.3