Methods and apparatus for analyzing a sample in the presence of interferents

• US 8,163,162 B2
• Filed: 03/31/2006
• Issued: 04/24/2012
• Est. Priority Date: 03/31/2006
• Status: Active Grant

• Current Assignee: Cilag Gmbh International (Johnson & Johnson), LifeScan IP Holdings, LLC
• Original Assignee: Lifescan Incorporated (Duv Holding Corporation)
• Inventors: Chatelier, Ronald C., Hodges, Alastair McIndoe, Verity, Bruce
• Primary Examiner(s): Noguerola, Alex
• Assistant Examiner(s): Kaur, Gurpreet
• Application Number:
  US11/278,341
• Publication Number:
  US 20070227912A1
• Time in Patent Office: 2,216 Days
• Field of Search: 20440301-40314, 204/415, 204/416, 204/408, 204450-455, 204600-605, 2057775-779, 205/775, 205/792, 435/817
• US Class Current: 205/792
• CPC Class Codes: A61B 5/1486 using enzyme electrodes, e.g. with immobilised oxidase
• 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

Abstract

Disclosed herein are methods and apparatus for determining analyte concentration in a rapid and accurate manner. The methods include depositing a physiological sample in an electrochemical cell and finding a first and second current transient. Peak current values are obtained from the first and second peak current values and used to reduce the influence of interferents in a current value. Based on this “corrected” current value, an accurate analyte concentration can be determined.

Claims

1. A method for reducing the effect of interferent in a test for analyte concentration, comprising:

(a) introducing a physiological sample into an electrochemical cell, the electrochemical cell comprising;

(i) first and second electrodes in a spaced apart relationship; and

(ii) a first reagent;

(b) applying a first test potential between said first and second electrodes, the first test potential having a first polarity and measuring cell current to obtain a first peak current value;

(c) applying a second test potential between said first and second electrodes, the second test potential having a second polarity, and measuring cell current to obtain a second peak current value;

(d) calculating an interference correction factor based on the first and second peak current values, wherein the interference correction factor can be used in a glucose concentration calculation to reduce the influence of chemical interferent compounds that will generate an interferent current by an oxidation or reduction reaction.

2. The method of claim 1, wherein the step (c) further includes measuring cell current as a function of time to obtain a second current transient and calculating a first current value based on the second current transient.

3. The method of claim 2, further comprising the step of calculating a corrected first current value by removing an interferent current value from the first current value.

4. The method of claim 3, wherein the step of calculating a corrected first current value includes multiplying the first current value by an interferent correction equation, wherein the interferent correction equation is

5. The method of claim 4, wherein the method further includes the steps of calculating a second current value based on the second current transient and measuring cell current as a function of time in step (b) to obtain a first current transient and calculating a third current value based on the first current transient.

6. The method of claim 5, further comprising the step of calculating an analyte concentration based upon an equation

7. The method according to claim 1, wherein the first reagent layer is disposed on the first electrode.

8. The method according to claim 7, wherein the first polarity is negative with respect to the second electrode and the second polarity is positive with respect to the second electrode.

9. The method according to claim 8, wherein a second reagent layer is disposed on the second electrode, wherein the second reagent layer comprises a redox mediator and is substantially free of the enzyme, and the redox mediator is capable of oxidizing an interferent present in the physiological sample.

10. The method of claim 1, wherein step (c) further includes measuring cell current as a function of time to obtain a second current transient.

11. The method of claim 1, wherein an analyte concentration is calculated based upon an equation

12. The method of claim 11, wherein the term i_pp is an average current over a short period of time near the end of the second current transient.

13. A method for reducing the effect of interferent in a test for analyte concentration, comprising:

(a) introducing a physiological sample into an electrochemical cell, the electrochemical cell comprising;

(i) a first reagent; and

(ii) two or more electrodes, the two or more electrodes consisting of a single working electrode and one or more other electrodes in a spaced apart relationship;

(b) applying a first test potential between the single working electrode and the one or more other electrodes, the first test potential having a first polarity, and measuring cell current to obtain a first peak current value;

(c) applying a second test potential between the single working electrode and the one or more other electrodes, the second test potential having a second polarity, and measuring cell current to obtain a second peak current value;

(d) calculating an interference correction factor based on the first and second peak current values, wherein the interference correction factor can be used in a glucose concentration calculation to reduce the influence of chemical interferent compounds that will generate an interferent current by an oxidation or reduction reaction.

14. The method of claim 13, wherein the two or more electrodes consist of a single working electrode and a single reference electrode.