An MRI method to detect and confirm analytes

A method for detecting whether or not an analyte is present in a sample using magnetic resonance, the method comprising: applying a first magnetic field to a sample comprising a liquid and material to be analyzed; applying a second magnetic field within at least one region of the sample so that the magnetic resonance signals of the liquid in the at least one region are different from the magnetic resonance signals of the outer liquid to the at least one region, where the second magnetic field is created by a nanoparticle associated with an affinity material in the presence of the first magnetic field, where the nanoparticle is a paramagnetic particle; retaining the analyte with the affinity material in the at least one region so that liquid moves from the at least one region; excite the magnetic resonance signals of the liquid while the analyte is in the at least one region to determine the T2 of the sample; and determine the presence of the analyte by determining if the determined T2 is greater than the T2 of the combination of the liquid with the paramagnetic particles, wherein the determination of T2 of the sample used to determine the presence of the analyte is performed before substantial agglomeration, and where the stoichiometry of the paramagnetic particles inhibits agglomeration.