Abstract: Method for assaying a target analyte in a biological sample in liquid medium, comprising: contacting the sample with first magnetic particles bearing a first receptor specific to a first analyte site of attachment to form first complexes; applying a first magnetic field to locally combine the formed complexes formed and optionally to agglomerate interfering complexes to form interfering aggregates; negating the applied magnetic field; adding second magnetic particles to a liquid medium that bear a second receptor specific to a second analyte site of attachment; measuring a first quantity of interfering aggregates; applying a second magnetic field to form second complexes; measuring a second quantity of the collective amount of interfering aggregates and second complexes to determine an amount of formed second complexes as a function of the first quantity, and deducing the amount of analyte present in the sample and, optionally, the amount of interfering analyte.