Embodiments include methods (and related systems, devices, and apparatuses) for determining a sorption separation factor for a binary gas mixture by applying a magnetic field to at least a portion of a sorbent (604) disposed in a chamber of a magnetic susceptibility device; directing a first gas stream including a first gas compound into the chamber at a first pressure and temperature to obtain a first magnetic susceptibility measurement; directing a second gas stream including a second gas compound into the chamber at a second pressure and temperature to obtain a second magnetic susceptibility measurement; directing a binary gas mixture including the first gas compound and the second gas compound into the chamber at a third pressure and temperature to obtain a third magnetic susceptibility measurement; and determining a sorption separation factor based on the first, the second, and the third magnetic susceptibility measurements.