The flash vaporizer injection port instanteneously vaporizes the
injected sample before it is introduced onto the column. This is
achieved by maintaining a temperature of the port that is higher that
the highest boiling substituent in the sample, often around
150oC.
Things to notice are:
When injecting a liquid or vapor, a quick expansion of the
volume occurs upon injection due to the evaporation of the liquid
and at the same time increase in the temperature, which makes the
vapor itself expand.
When a liquid is inject a little bit will remain inside the
needle of the syringe. This means that in order to have the
narrowest plug introduced on the column one needs to avoid that
material from more slowly evaporating and 'leaking' into the
injection port, i.e., one should retract the needle
immediately after the material is injected.
Depending on the detector used, one can also make sure that a
little bit of air is present in the syringe so that the retention
time of an non-retained compound can be determined at the same
time.
The injection is done quickly emptying a syringe stuck through a
septum (see the quicktime movie below)