Abstract: There is described a method for the preparation of an aqueous magnetic resonance imaging medium, said method comprising the steps of: •(i) preparing a multiphasic solvent system comprising an aqueous component and a non-aqueous component, said solvent comprising a target substrate and a SABRE hyperpolarisation transfer catalyst; •(ii) adding H2 or parahydrogen gas; •(iii) agitating the solvent system to form an emulsion thereby transferring the spin order from the hyperpolarisation transfer catalyst to the target substrate; •(v) adding a solvent phase-separation promoter; and •(vi) separating the non-aqueous component and the aqueous component wherein the aqueous component contains the hyperpolarised target substrate and provides the aqueous magnetic resonance imaging medium.