Injected sample enters column immediately (while split valve to split vent is closed). Here a sample is introduced into a heated small chamber via a syringe through a septum - the heat facilitates volatilization of the sample and sample matrix. The carrier gas then either sweeps the entirety (splitless mode) or a portion (split mode) of the sample into the column. In split mode, a part of the sample/carrier gas mixture in the injection chamber is exhausted through the split vent.