steam distillation
Steam distillation is a special type of distillation (a separation
process) for temperature sensitive materials that tend to decompose at
sustained high temperatures. Separation by normal distillation would
then not be an option, so water or steam are introduced into the
distillation apparatus. By adding water or steam the boiling point of
the compounds is depressed, allowing them to evaporate at lower
temperatures, preferably below the temperatures at which the
deterioration of the material becomes appreciable. If the substances to
be distilled are very sensitive to heat, steam distillation can also be
combined with vacuum distillation. After destillation the vapors are
condensed as usual, usually yielding a two-phase system of water and
the organic compounds, allowing for simple separation.
Steam distillation has been evaluated as a technique for the separation
of methylmercury from different environmental sample materials.
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