Trace Analysis of Biological Materials by Mass Spectrometry and Isotope Dilution. Survey Paper

The life processes of every living cell are conditioned by its content of trace elements. Throughout the search for essential elements, the state of knowledge of the essentiality of elements in biology has never been far removed from the process of development of more sensitive and reliable analytical methods for the detection and measurement of the trace elements. One of the most sensitive and comprehensive techniques of trace analysis is mass spectrometry and its application to biological problems is becoming increasingly apparent. Although mass spectrometry is capable of providing information on both the elemental and molecular composition of biological materials, only the former is treated here. Among the methods of excitation for elemental analysis reviewed here are the vacuum spark, electron bombardment, thermal ionization and ion bombardment. Because of its many advantages, particular emphasis is placed on the role of spark-source mass spectrometry in the determination of trace elements in animal tissue, body fluids and plant material. The isotope dilution technique, which is essentially an internal standard method involving stable isotopes, provides mass spectrometry with some of its most sensitive and precise methods of elemental analysis, with reproducibilities on the order of ±0.1%. Its application to biological problems is discussed. Finally, the advantages and limitations of mass spectrometry are compared with those of activation analysis. (author)