Method of reducing interferences in an electrochemical sensor using two different applied potentials

• US 7,618,522 B2
• Filed: 10/29/2004
• Issued: 11/17/2009
• Est. Priority Date: 10/31/2003
• Status: Expired due to Fees

• Current Assignee: Cilag Gmbh International (Johnson & Johnson)
• Original Assignee: LifeScan Scotland Limited (Johnson & Johnson)
• Inventors: Davies, Oliver William Hardwicke
• Primary Examiner(s): Nguyen; Nam X
• Assistant Examiner(s): BALL, JOHN C
• Application Number:
  US10/977,154
• Publication Number:
  US 20050183965A1
• Time in Patent Office: 1,845 Days
• Field of Search: 204/403.14, 205/775, 205/777.5, 205/792
• US Class Current: 204/403.14
• CPC Class Codes: A61B 5/14532 for measuring glucose, e.g. by tissue impedance measurement
• CPC Class Codes: A61B 5/1486 using enzyme electrodes, e.g. with immobilised oxidase
• CPC Class Codes: A61B 5/150022 for capillary blood or interstitial fluid
• CPC Class Codes: A61B 5/150282 for piercing elements, e.g. blade, lancet, canula, needle
• CPC Class Codes: A61B 5/150358 Strips for collecting blood, e.g. absorbent optical reagent test strips G01N21/8483; chemical reagent test strips G01N33/4875, G01N33/52
• CPC Class Codes: A61B 5/150435 Specific design of proximal end
• CPC Class Codes: A61B 5/150503 Single-ended needles hollow piercing element tip design A61B5/150396, needle sets for catheters A61M25/06, needles for bringing media into the body A61M5/32
• CPC Class Codes: C12Q 1/001 Enzyme electrodes
• CPC Class Codes: C12Q 1/006 for glucose
• CPC Class Codes: G01N 27/3274 Corrective measures, e.g. error detection, compensation for temperature or hematocrit, calibration coding of calibration information G01N33/48771
• CPC Class Codes: Y02A 90/10 Information and communication technologies [ICT] supporting adaptation to climate change, e.g. for weather forecasting or climate simulation

Abstract

The present invention is directed to a method of reducing the effects of interfering compounds in the measurement of analytes and more particularly to a method of reducing the effects of interfering compounds in a system wherein the test strip utilizes two or more working electrodes. In one embodiment of the present invention, a first potential is applied to a first working electrode and a second potential, having the same polarity but a greater magnitude than the first potential, is applied to a second working electrode.

Claims

1. A method of reducing interferences in an electrochemical sensor having a sample chamber with first and second working electrodes disposed in the chamber, the working electrodes including a reagent disposed thereon, the method comprising:

contacting a sample of physiological fluid with the working electrodes and reagent, the physiological fluid including at least an analyte disposed therein;

applying a first potential to the first working electrode to initiate a chemical reaction;

applying a second potential to the second working electrode to initiate a chemical reaction, wherein said second potential is greater than the absolute value of said first potential;

measuring a first current, at said first working electrode, which comprises an analyte current and an interfering compound current;

measuring a second current, at said second working electrode, which comprises an analyte overpotential current and an interfering compound overpotential current, wherein said analyte overpotential current has a first directly proportional relationship to said analyte current, the first directly proportional relationship comprising

X×

A₁=A₂

where X is said analyte voltage effect factor derived from calibration test data of the sensor, A₁ is said analyte current, and A₂ is said analyte overpotential current and, wherein said interfering compound overpotential current has a second directly proportional relationship to said interfering compound current, the second directly proportional relationship is

Y×

I₁=I₂

where Y is said interfering compound voltage effect factor, I₁ is said interfering compound current, and I₂ is said interfering compound over potential current; and

calculating a corrected current value representative of an analyte concentration of the physiological fluid using an equation which is a function of said first current, said second current, said first directly proportional relationship, and said second directly proportional relationship.

2. The method of claim 1, wherein said equation is

3. The method of claim 1, wherein said analyte is glucose.

4. The method of claim 1, wherein said first potential is between about 385 millivolts and about 415 millivolts for said electrochemical sensor which comprises a carbon working electrode and a ferrocyanide redox mediator.

5. The method of claim 1, wherein said second potential is between about 420 millivolts and about 1000 millivolts for said electrochemical sensor which comprises a carbon working electrode and a ferrocyanide redox mediator.

6. The method of claim 1, wherein said interfering compound current results from the oxidation of at least one chemical chosen from the group consisting of acetaminophen, ascorbic acid, bilirubin, dopamine, gentisic acid, glutathione, levodopa, methyldopa, tolazimide, tolbutamide, and uric acid.