The analysis of solid material usually requires a dissolution/
digestion stage prior to introduction to most atomic spectrometric
techniques. This normally involves use of an acid digestion procedure,
the constituents of which would depend largely on the sample
type and of the level of digestion required. Transforming the solid
material into a liquid form so that it may be introduced more easily
to the analytical instrumentation has the drawback of diluting the
analytes present. Typically, such digestions lead to dilution factors
of between 25 and 100. Other dissolution procedures, e.g. fusions
add substantial amounts of solid material to the mixture and may
therefore require even greater dilutions (e.g. by a factor of 1000) so
that the sample is not too viscous.
Dilutions of 100 or greater will often place many of the most
toxic metals near or even below the limit of detection by flame
atomic absorption spectrometry (FAAS) and by inductively coupled
plasma-atomic emission spectrometry (ICP-OES) which, for many
analytes, have a limit of detection of approximately 0.01 mg L−1.