Methods of dispensing meted quantities of hyperpolarized gas to form a hyperpolarized gas mixture include pre-filling a gas syringe with a quantity of non-polarized gas, then introducing the hyperpolarized gas therein while the non-polarized gas is held therein, and expelling both the hyperpolarized gas and non-polarized gas from the syringe. Methods of inhibiting the presence of oxygen in gas flow paths and extraction systems are also described.