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Atomic Absorption Spectrophotometry (AAS) is an analytical
technique used to measure a wide range of elements in materials
such as metals, pottery and glass. Although it is a destructive
technique (unlike ED-XRF), the sample size needed is very small
(typically about 10 milligrams - i.e. one hundredth of a gram)
and its removal causes little damage. The sample is accurately
weighed and then dissolved, often using strong acids. The
resulting solution is sprayed into the flame of the instrument
and atomised (see schematic diagram). Light of a suitable
wavelength for a particular element is shone through the flame,
and some of this light is absorbed by the atoms of the
sample. The amount of light absorbed is proportional to the
concentration of the element in the solution, and hence in the
original object. Measurements are made separately for each
element of interest in turn to achieve a complete analysis of
an object, and thus the technique is relatively slow to
use. However, i t is very sensitive and it can measure trace
elements down to the part per million level, as well as being
able to measure elements present in minor and major amounts.
Additional information available at
"http://www.thebritishmuseum.ac.uk/science/text/techniques/
sr-tech-aas-t.html"
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