Most often, a solution containing the sample is injected. The target
concentration is dependent on the detector used and the operational
parameters of the detector. Some detectors can be damaged by injection
of solutions that are too concentrated.
Aqueous solutions are not used.
Most often, the sample is flash vaporized in the inlet for deposition
onto the column. The inlet is therefore heated; analytes should be
sufficiently volatile to be vaporized. Some compounds may decompose
at the inlet temperature, these require different introduction techniques.
There are three basic inlet techniques used with capillary GC: split, splitless and pulsed splitless. There are other techniques as well.