High-performance liquid magneto-chromatography (HPLMC) is a new chromatography technique with two distinctive features: (a) a high surface area stationary phase with paramagnetic properties composed of magnetite embedded in a silica gel, and (b) a magnetic field (variable intensity 0-5.5 mT) that selectively retains paramagnetic substances in the stationary phase depending on their magnetic susceptibility. The system can also be used to separate diamagnetic compounds such as biologically active organic molecules, but these first need to be complexed with Fe and Cu compounds to render them paramagnetic. Herein, we describe the experimental setup and the relationship between the retention factor and the magnetic field intensity, i.e., the force interaction of the complexes in relation to the magnetized magnetite. The expression derived also provides the effective magnetic susceptibility (Deltachi) of the components separated.