In one aspect, a method of extracting a target analyte from a sample for introduction into a mass spectrometer is disclosed, which includes mixing the sample with a paramagnetic medium to form a mixture, subjecting the mixture to a magnetic field gradient to form a non-homogenous distribution of at least one of the analyte and at least one interfering component of the sample, if any, thereby enhancing a concentration of the target analyte within a spatial location of said mixture, extracting at least a portion of the target analyte from that spatial location, and introducing at least a portion of the extracted target analyte into said mass spectrometer.