Analyte determination method and analyte meter
First Claim
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1. A method for determining an analyte in a sample comprising the steps of:
- (a) placing the sample in an electrochemical test cell comprising a working and a counter electrode and a mediator that serves as a charge carrier in the electrochemical determination of the analyte,(b) electrochemically determining an uncorrected result for the determination of analyte in the sample;
(c) determining an additive correction factor for the amount of oxygen in the sample, and(d) modifying the uncorrected result of step (b) with the correction factor of step (c) to provide a corrected determination of analyte in the sample,wherein the additive correction factor for the amount of oxygen in the sample is determined as a function of the temperature of the sample and a measurement that reflects the oxygen carrying capacity of the sample, wherein the sample is a blood sample, the measurement that reflects the oxygen carrying capacity is hematocrit (hct) and the additive correction factor is given by the equation
additive correction factor=constant×
[(S×
T)+I]×
hct wherein T is the temperature,S and I are the slope and intercept, respectively, of a plot in which the y axis is the slope of a line plotting uncorrected analyte measurement as a function of hematocrit and the x axis is temperature, andconstant is an empirically determined constant for the particular apparatus and method of determining hematocrit.
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Abstract
The presence of oxygen or red blood cells in a sample applied to an electrochemical test strip that makes use of a reduced mediator is corrected for by an additive correction factor that is determined as a function of the temperature of the sample and a measurement that reflects the oxygen carrying capacity of the sample. The measured oxygen carrying capacity can also be used to determine hematocrit and to distinguish between blood samples and control solutions applied to a test strip.
43 Citations
33 Claims
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1. A method for determining an analyte in a sample comprising the steps of:
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(a) placing the sample in an electrochemical test cell comprising a working and a counter electrode and a mediator that serves as a charge carrier in the electrochemical determination of the analyte, (b) electrochemically determining an uncorrected result for the determination of analyte in the sample; (c) determining an additive correction factor for the amount of oxygen in the sample, and (d) modifying the uncorrected result of step (b) with the correction factor of step (c) to provide a corrected determination of analyte in the sample, wherein the additive correction factor for the amount of oxygen in the sample is determined as a function of the temperature of the sample and a measurement that reflects the oxygen carrying capacity of the sample, wherein the sample is a blood sample, the measurement that reflects the oxygen carrying capacity is hematocrit (hct) and the additive correction factor is given by the equation
additive correction factor=constant×
[(S×
T)+I]×
hctwherein T is the temperature, S and I are the slope and intercept, respectively, of a plot in which the y axis is the slope of a line plotting uncorrected analyte measurement as a function of hematocrit and the x axis is temperature, and constant is an empirically determined constant for the particular apparatus and method of determining hematocrit. - View Dependent Claims (2, 3, 4, 5)
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6. A meter apparatus for receiving an electrochemical test strip having electrodes and providing a determination of an analyte in a sample applied to the electrochemical test strip when received in the meter, said meter comprising
(a) a housing having a slot for receiving an electrochemical test strip; -
(b) communications means for receiving input from and communicating a result to a user; and (c) means for determining an uncorrected result for the determination of analyte in the sample, determining an additive correction factor for the amount of oxygen in the sample, and modifying the uncorrected result with the correction factor of step (c) to provide a corrected determination of analyte in the sample, wherein the additive correction factor for the amount of oxygen in the sample is determined as a function of the temperature of the sample and a measurement that reflects the oxygen carrying capacity of the sample, wherein the measurement that reflects the oxygen carrying capacity is hematocrit (hct) and the additive correction factor is given by the equation
additive correction factor=constant×
[(S×
T)+I]×
hctwherein T is the temperature, S and I are the slope and intercept, respectively, of a plot in which the y axis is the slope of a line plotting uncorrected analyte measurement as a function of hematocrit and the x axis is temperature, and constant is an empirically determined constant for the particular apparatus and method of determining hematocrit. - View Dependent Claims (7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31)
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32. A method for determination of analyte in which a material is applied to an electrochemical test strip disposed in an analyte detection apparatus, wherein the material may be either a blood sample or a control solution and the signal from the test strip is processed as test sample or a calibration run based on this identification, wherein, the identification of the material as a sample or control solution is performed by the steps of:
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(a) applying a potential for period for time sufficient to establish a chemical potential gradient between electrodes of the electrochemical test strip, (b) switching off the applied potential at a time tswitch, and obtaining a value indicative of the rate of decay of the chemical potential gradient in the absence of applied potential, and (c) comparing the determined value of the rate of decay with a threshold value, wherein a value on one side of the threshold value indicates that the material is a blood sample, and a value on the other side of the threshold value indicates that the material is a control solution.
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33. An apparatus for determination of analyte in which a material is applied to an electrochemical test strip disposed in an analyte detection apparatus, wherein the material may be either a blood sample or a control solution and the signal from the test strip is processed as test sample or a calibration run based on this identification, wherein, the identification of the material as a sample or control solution is performed by the steps of:
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(a) means for applying a potential for period for time sufficient to establish a chemical potential gradient between electrodes of the electrochemical test strip, (b) means for switching off the applied potential at a time tswitch, and obtaining a value indicative of the rate of decay of the chemical potential gradient in the absence of applied potential, and (c) means for comparing the determined value of the rate of decay with a threshold value, wherein a value on one side of the threshold value indicates that the material is a blood sample, and a value on the other side of the threshold value indicates that the material is a control solution.
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Specification