US 5,650,061 AGranted

Large amplitude sinusoidal voltammetry

AssigneeThe Regents of the University of California

InventorsWerner G. Kuhr, John K. Cullison

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Abstract

A large amplitude sine wave is applied as the excitation potential to a amperometric measurement to produce a current output that is a phase shifted sine wave containing faradaic information at many frequencies. A current obtained from a conventional potentiostat coupled to the electrode is coupled to a lock-in amplifier that monitors the signal at one frequency at a specified phase angle. Since most of the background remains at the fundamental frequency, a higher harmonic of the fundamental frequency of the sinusoidal sweep frequency is monitored. By locking in on the higher harmonic components, the faradaic signal is therefore distinguished from the background signal. The background is diminished thereby allowing signal recognition at low analyte concentrations and increasing the signal-to-noise ratio.

Claims13

Dependent claims

A method for making a fast electrochemical analysis in a voltammetric flow injection system of a small volume of analyte having at least one redox species of interest with a formal potential included within a potential window, the method comprising:

providing a small amount of said analyte in a flow to a voltammetric electrode;
applying a sinusoidal voltage characterized by a fundamental frequency to said electrode, said sinusoidal voltage having an amplitude large enough to sweep through said formal potential of said redox species of interest of said analyte in a single cycle at said fundamental frequency to generate a voltammetric response of said analyte to said sinusoidal voltage in a time domain;
and
generating a Fourier transform of said voltammetric response of said analyte to said sinusoidal voltage in said time domain to provide a spectrum of said voltammetric response in a frequency domain;
selectively quantifying said voltammetric response of said analyte to said sinusoidal voltage in said frequency domain at a harmonic of said fundamental frequency of said sinusoidal voltage rather than at said fundamental frequency without inversely transforming said voltammetric response back to said time domain to provide a quantitative analysis of said analyte,
whereby a complete frequency spectrum is obtained within one cycle of said sinusoidal voltage.

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Dependencies are inferred from the claim text.