Methods for detecting one or more analytes in a sample utilizing Electrochemical Impedance Spectroscopy (EIS) measurement. In one method, analyte detection includes comparing an imaginary impedance measurement to a calibration curve of concentrations for each target analyte. The calibration curve of concentrations for each target analyte is established at an optimal frequency. In another method, a signal decoupling algorithm is utilized for detection of more than one analyte on an electrode.