SINGLE MOLECULE MASS OR SIZE SPECTROMETRY IN SOLUTION USING A SOLITARY NANOPORE

A nanopore conductance measurement method and system is provided. The system has reservoirs of conductive fluid separated by a resistive barrier, which is perforated by a single nanometer scale pore commensurate in size with an analyte molecule in at least one of the reservoirs. The system is configured to have an ionic current driven across the reservoirs by an applied potential and the pore may be treated so that the pore surface can form associations with the analyte molecules of interest to increase the analyte molecule residence times on or in the pore. The system also comprises a means of measuring the ionic current, which current may be either direct or alternating in time, induced by an applied potential between electrodes in the conductive fluid, on each side of the barrier. The system also comprises a means of recording the ionic current time course as a time series, which includes time periods when the pore is unobstructed and also in periods when analyte molecules cause pulses of reduced conductance. The method comprises methods to delineate segments of the conductance time series into regions statistically consistent with the unobstructed pore conductance level, and pulses of reduced conductance, and also statistically stationary segments within individual pulses of reduced conductance. The method may also provide steps for interpreting the statistical analysis to yield parameters such as size, mass, and/or concentration of at least one type of analyte in solution.