Method for measuring sample by enzyme electrodes

• US 5,407,545 A
• Filed: 04/25/1994
• Issued: 04/18/1995
• Est. Priority Date: 04/30/1993
• Status: Expired due to Term

• Current Assignee: Kyoto Daiichi Kagaku Company Limited
• Original Assignee: Kyoto Daiichi Kagaku Company Limited
• Inventors: Hirose, Kazunori
• Primary Examiner(s): Niebling, John
• Assistant Examiner(s): Bell, Bruce F.
• Application Number:
  US08/231,665
• Time in Patent Office: 358 Days
• Field of Search: 204/153.12, 204/153.1, 435/4, 435/14, 435/10
• US Class Current: 205/777.5
• CPC Class Codes: C12Q 1/001 Enzyme electrodes

Abstract

A buffer solution is charged in a reaction container so that enzyme electrodes can be immersed in the buffer solution. Current values between the enzyme electrodes, to which a voltage is applied, are sampled at predetermined-time intervals. A decreasing curve of current is predicted on the basis of the sampled current values. A sample is injected in said buffer solution at an early time before the current between enzyme electrodes become stable, whereby oxidation reaction of a specified component of the sample is caused. A current value I₁ between enzyme electrodes is measured and simultaneously a current value T₂ on the decreasing curve is obtained at a point that a predetermined time passes from the sample injection point to obtain a current increase from the sample injection on the basis of a difference of the current values I₁ and I₂. A quantity of the specified component of the sample is obtained on the basis of the current increase.

Claims

1. A method for measuring sample by enzyme electrodes comprising the following steps of:

charging a buffer solution in a reaction container so that said enzyme electrodes can be immersed in said buffer solution;

sampling current values between said enzyme electrodes, to which a voltage is applied, at set-time intervals;

predicting a decreasing curve of current on the basis of said current values;

injecting a sample in said buffer solution at an early time before said current between enzyme electrodes become stable, whereby oxidation reaction of a specified component of said sample is caused;

measuring a current value I₁ between said enzyme electrodes and simultaneously obtaining a current value I₂ on said decreasing curve at a point that a set time passes from said sample injection point to obtain a current increase from said sample injection on the basis of a difference of said current values I₁ and I₂ ; and

obtaining a quantity of said specified component of said sample on the basis of said current increase.

3. A method according to claim 1 or 2, wherein said decreasing curve is predicted by a least square method.

4. A method according to claim 1 or 2, wherein said step of predicting a decreasing curve of current is prosecuted at every time of measurement of each sample.

5. A method according to claim 1 or 2, wherein said sample is a blood.

6. A method according to claim 1 or 2, wherein said sample is a blood serum.

7. A method according to claim 1 or 2, wherein said sample is a blood plasma.

8. A method according to claim 1 or 2, wherein said sample is a urine.

9. A method according to claim 1 or 2, wherein said specified component is a glucose.

10. A method according to claim 1 or 2, wherein said specified component is a uric acid.

11. A method according to claim 1 or 2, wherein said sample is a lactic acid.

2. A method for measuring sample by enzyme electrodes comprising the following steps of:

charging a buffer solution in a reaction container so that said enzyme electrodes can be immersed in said buffer solution;

sampling current values between said enzyme electrodes, to which a voltage is applied, at set-time intervals;

predicting a decreasing curve of current on the basis of said current values to obtain a differential decreasing curve by differentiating said decreasing curve;

injecting a sample in said buffer solution at an early time before said current between enzyme electrodes become stable, whereby oxidation reaction of a specified component of said sample is caused;

obtaining a differential reaction curve by differentiating a reaction curve of current measured under said oxidation reaction;

obtaining a differential current value dI₁ on said differential reaction curve and a differential current value dI₂ on said differential decreasing curve at a peak point of said differential reaction curve to obtain a current increase from said sample injection on the basis of a difference of said differential current values dI₁ and dI₂ ; and

obtaining a quantity of said specified component of said sample on the basis of said current increase.