Factors that influence the distribution of trace element-containing chemical species in living systems before and after sample collection.

The identification and characterisation of the various species of a trace element in a system could provide important clues as to its biochemical role(s). In order that the results of experiments reflect the true situation in the system under study at the time the sample was taken, chemical and physical changes that can affect the distribution profile of a given element have to be understood and controlled. A number of factors that can influence the nature and form of chemical species before, during and after sampling of biological systems have been identified and discussed. Precautions that could help in limiting such changes are recommended.