Method for determining the concentration of electro-chemically convertible substances

• US 4,919,770 A
• Filed: 12/19/1986
• Issued: 04/24/1990
• Est. Priority Date: 07/30/1982
• Status: Expired due to Fees

• Current Assignee: Siemens AG
• Original Assignee: Siemens AG
• Inventors: Preidel, Walter, Mund, Konrad
• Primary Examiner(s): Nguyen, Nam X.
• Application Number:
  US06/945,065
• Time in Patent Office: 1,222 Days
• Field of Search: 204/1 T, 204/1 P, 204/1 K, 204/1 Y, 204/1 B, 204/406, 204/403, 204/415, 128/635
• US Class Current: 205/780.5
• CPC Class Codes: G01N 33/48714 for determining substances foreign to the organism, e.g. drugs or heavy metals drugs by chemical analysis G01N33/94

Abstract

The invention involves a method for determining the concentration of electro-chemically convertible substances in a solution by means of an analyzer equipped with a test electrode, so that a precise determination of the concentration, dependable over extended periods, is possible. The invention provides for a potential varying with time within a potential interval to be impressed on the test electrode, for an ac voltage of a predetermined amplitude and frequency to be superimposed on this potential, and for the real and/or imaginary portions of the impedance to be determined for at least one potential step, thus determining the concentration. The method is particularly suited for determining the concentration of glucose in body fluids.

Claims

1. A method for determining the concentrations of glucose, urea and/or amino acids in the presence of each other in a solution by means of an electrochemical sensor comprising a membrane-covered platinum test electrode and a counter electrode, comprising:

contacting the platinum test electrode with a physiological solution which contains glucose, urea and amino acids;

impressing a potential varying with time on the platinum test electrode in potential steps within a potential interval;

superimposing AC voltage of predetermined amplitude and predetermined different frequencies on the potential during at least one potential step;

establishing the real and imaginary portions of the impedance during said at least one potential step; and

determining the concentration of glucose, urea and/or amino acids from the real and imaginary portions of the impedance established during said at least one potential step.