Hi, are there any experimentalists here? I have gas in a cylinder. I have just been taking samples of gas from a tube connected to the outlet, but air is getting in the syringe. So I went over to chemistry and got a round bottom flask with 3 inlets / outlets and a septum, so its like this: I evacuate the flask with the vacuum then flow the gas in, then after about a minute I pierce the septum with the GC syringe and take in some gas. I am still getting air in the gas sample! Does anyone know a standard way of extracting gas from a cylinder (into a GC syringe) without air getting into it? Any help would be really appreciated. I can order glassware etc etc but I dont know what specific equipment I need.