Abstract: The present invention provides a system for filling a syringe with a small amount of a more precisely mixed medical gas mixture, the system comprising two or more sources for gas, a device for mixing the gases, a means for connecting the gas sources to the device for mixing the gases, a filter system and a syringe. The present invention further provides for a process for filling a syringe with a small quantity of a thoroughly mixed medical gas mixture comprising at least a first gas and a second gas. The process comprises the steps of providing at least a first gas and a second gas, injecting the gases into a device for mixing to form a thoroughly mixed medical gas mixture, filtering the medical gas mixture, and filling a syringe with the required amount of medical gas mixture.