Production of hyperpolarized gas

A method of producing a hyperpolarized noble gas, comprising:

• mixing a noble gas with an initial buffer gas to form a mixture such that the noble gas is present in the mixture at a first concentration;
• spin-exchange optical pumping the mixture to hyperpolarize the noble gas;
• and
• removing the buffer gas from the mixture so as to isolate the hyperpolarized noble gas whilst maintaining the hyperpolarization by:
• reacting the buffer gas present in the mixture comprising the buffer gas and hyperpolarized noble gas to produce a reaction product different to the buffer gas, wherein reacting the buffer gas comprises at least one of:
• (i) oxidising the buffer gas by one or more of combustion and induced plasma;
• (ii) introducing oxygen (O2) into the mixture comprising the buffer gas and the hyperpolarized noble gas, and combusting the buffer gas;
• (iii) introducing oxygen (O02) into the mixture comprising the buffer gas and the hyperpolarized noble gas in the presence of a catalyst, and catalytically removing the buffer gas;
• (iv) passing the mixture comprising the buffer gas and the hyperpolarized noble gas over or through an oxidizing agent;
• and
• (v) oxidizing an alkaline earth metal using the buffer gas.