We have been using an Agilent 7890B GC-MS with FID TCD equipped with an autosampler (ALS) for analysing liquid hydrocarbon samples. I would like to analyse gaseous samples of CO, CO2 and H2 in the future. Is it possible to manually inject gas samples in this system directly, or is it necessary to install other accessories before analysing gas samples by manual injection? The system is not equipped with a gas sampling valve.