Abstract: An apparatus for analyzing a sample of a mixture of compounds selected from the group consisting of polynucleotides, proteins and fragments thereof attached to magnetized moieties which generate a magnetic field contained on a substrate comprising:a) a support for mounting the substrate,b) a magnetic field detector mounted adjacent the substrate, the magnetic field detector generating an electrical signal in response to a magnetic field from the substrate,c) scanning means for moving the magnetic field detector relative to the substrate, andd) an amplifier operatively connected to the magnetic field detector to amplify a signal generated thereby.