Method and device for the determination of an analyte using super paramagnetic reactive particles

A process for determining the presence or quantity of an analyte in a sample, comprising:

• i) providing said sample in a liquid phase, in which the analyte comprises a ligand having at least one site for specific recognition of an antiligand;
• ii) providing at least one reagent comprising super-paramagnetic reactive metal particles in suspension in a liquid phase, each reactive particle comprising a metal core onto which at least one said anti-ligand is bound directly or indirectly;
• iii) contacting the sample and the reagent in order to obtain, in a liquid phase, an intermediate mixture of metal complexes of the reactive particles which have reacted with the analyte, and unreacted residual reactive particles;
• iv) applying a magnetic field having magnetic lines to the intermediate mixture;
• and
• v) detecting the metal complexes in order to obtain a detection signal representing at least one of a presence and a quantity of said metal complexes, said signal being correlated with at least one of said presence and said quantity of said analyte originally present in the sample,
• wherein:
• a) according to step (iv) with the magnetic field applied to the intermediate mixture, the metal complexes of the reactive particles which have reacted with the analyte are confined, in a form of a measurement aggregate, and said aggregate is separated from the unreacted residual reactive particles;
• and
• b) according to step (v), the separated measurement aggregate is detected by measuring its ferromagnetic mass representing at least one of the presence and the quantity of said metal complexes.