The role of trace elements in biological systems has become prominent in clinical medicine during the past few years as reliable analytical methods suited to the clinical laboratory have been developed. The beginning of modern trace element analysis was the introduction of the flame photometer in the 1940's. This instrument is severely limited in its range; sodium, potassium, lithium, and to a lesser extent, calcium, barium, and magnesium are the only elements that can be quantitated readily by this technique. The availability of the much more versatile atomic absorption spectrophotometer in the early 1960's lead to the development of methods which allowed clinical laboratories to measure a large number of trace elements with relative ease.
Still, the lack of readily available literature on biological applications of atomic absorption spectrophotometry hindered its acceptance by the clinical laboratory. It was not until 1967 that slim volumes of biomedical orientation began to appear.