Apparatus for amperometric diagnostic anagnostic analysis
First Claim
1. A sample cell for determining the concentration of a selected compound in a sample aqueous fluid, comprising a first electrode which acts as a working electrode. a second electrode of substantially the same size as said first electrode and being made of the same electrically conducting material as said first electrode, said second electrode being operatively associated with said first electrode, and at least one non-conducting layer member having an opening therethrough, said layer member being disposed in contact with at least one of said electrodes and said layer member being sealed against at least one of said first and second electrodes to form a known electrode area within said opening such that said opening forms a well to receive said sample aqueous fluid and to place said fluid in said known electrode area in contact with said first electrode and second electrode, whereby substantially the entire contents of said well is capable of being substantially simultaneously subjected to a predetermined reaction.
0 Assignments
0 Petitions
Accused Products
Abstract
The present invention relates to a novel method and apparatus for the amperometric determination of an analyte, and in particular, to an apparatus for amperometric analysis utilizing a novel disposable electroanalytical cell for the quantitative determination of biologically important compounds from body fluids.
168 Citations
66 Claims
-
1. A sample cell for determining the concentration of a selected compound in a sample aqueous fluid, comprising
a first electrode which acts as a working electrode. a second electrode of substantially the same size as said first electrode and being made of the same electrically conducting material as said first electrode, said second electrode being operatively associated with said first electrode, and at least one non-conducting layer member having an opening therethrough, said layer member being disposed in contact with at least one of said electrodes and said layer member being sealed against at least one of said first and second electrodes to form a known electrode area within said opening such that said opening forms a well to receive said sample aqueous fluid and to place said fluid in said known electrode area in contact with said first electrode and second electrode, whereby substantially the entire contents of said well is capable of being substantially simultaneously subjected to a predetermined reaction.
-
4. An apparatus for measuring compounds in a sample fluid, comprising
a) a housing having an access opening therethrough. b) a sample cell receivable into said access opening of said housing, said sample cell being composed of a first electrode which acts as a working electrode, a second electrode which acts to fix the system potential and provide opposing current flow with respect to said first electrode, said second electrode being of substantially the same size as said first electrode and being made of the same electrically conducting material as said first electrode, said second electrode being operatively associated with said first electrode, at lease one non-conducting layer member having an opening therethrough, said layer member being and said layer member being sealed against at least one of said first and second electrode to form a known electrode area within said opening such that said opening forms a well to receive said sample fluid and to place said fluid in said known electrode area in contact with said first electrode and said second electrode, (c) means for applying an electrical potential to said first electrode and said second electrode, (d) means for creating an electrical circuit between said first electrode and said second electrode through said sample, (e) means for measuring Cottrell current through said sample and (f) means for visually displaying results of said measurement.
-
18. A method of measuring the amount of a selected compound in body fluids comprising:
-
a) providing a measuring cell having at least a first and second electrode of substantially the same size and made of the same electrically conductive material, said cell further containing an oxidant and a buffer, b) placing a sample of fluid to be tested in said cell, c) reconstituting said oxidant and buffer with said sample fluid to generate a predetermined reaction, d) allowing said reaction to proceed substantially to completion, e) applying a potential across said electrodes and sample, and f) measuring the resulting Cottrell current to determine the concentration of said selected compound present in said sample. - View Dependent Claims (19, 20, 27)
-
-
21. A method for measuring the amount of glucose in blood, comprising
a) providing a measuring cell having at least a f irst and second electrode of substantially the same size and made of the same electrically conductive material, said cell further containing an oxidant, a buffer and an enzyme, b) placing a blood sample to be tested in said cell, c) reconstituting said oxidant, buffer and enzyme with said blood sample to generate a predetermined reaction, d) essentially immediately applying a potential across said electrodes and blood sample, and e) measuring the resultant Cottrell current when the reaction has proceeded to completion to determine the concentration of said glucose present in said blood sample.
-
28. A method of measuring the amount of an analyte in a fluid sample, comprising:
-
a. adding the fluid sample to an electrochemical cell having at least a first and second electrode of substantially the same size and comprising the same electrically conductive material, said electrochemical cell including an electron transfer agent that will react in a reaction involving the analyte, thereby forming a detectable species;
b. incubating the reaction involving analyte and electron transfer agent in an open circuit for a specified period of time;
c. applying a sufficient potential difference between the electrodes of the electrochemical cell, after the incubation step, to readily transfer at least one electron between the detectable species and one of the electrodes, thereby resulting in a Cottrell current;
d. measuring the Cottrell current; and
e. correlating the measured Cottrell current to the amount of analyte in the fluid sample. - View Dependent Claims (29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45)
-
-
46. A method of measuring the amount of an analyte in a fluid sample, comprising:
-
a. adding the fluid sample to an electrochemical cell that includes at least a first and second electrode of substantially the same size and comprising the same electrically conductive material, wherein the conductive material is selected from the group consisting of palladium, platinum, gold, silver, and carbon, an electron transfer agent, a first catalyst in sufficient amount to catalyze a first reaction involving the analyte, and a second catalyst in sufficient amount to catalyze a second reaction involving a product of the first reaction and the electron transfer agent, thereby forming a detectable species;
b. incubating the first and second reactions in an open circuit for a specified period of time;
c. applying a sufficient potential difference between electrodes of the electrochemical cell, after the incubation step, to readily transfer at least one electron between the detectable species and one of the electrodes, thereby resulting in a Cottrell current;
d. measuring the Cottrell current; and
e. correlating the measured Cottrell current to the amount of analyte in the fluid sample. - View Dependent Claims (47, 48)
-
-
49. A method of measuring the amount of an analyte in a fluid sample, comprising:
-
a. adding the fluid sample to an electrochemical cell that includes first and second electron transfer agents, a first catalyst in sufficient amount to catalyze a first reaction involving the analyte, a second catalyst in sufficient amount to catalyze a second reaction involving a product of the first reaction and the first electron transfer agent, thereby forming an intermediate species that reacts with the second electron transfer agent, thereby forming a detectable species;
b. incubating the reactions of step a) in an open circuit for a specified period of time;
c. applying a sufficient potential difference between electrodes of the electrochemical cell having substantially the same surface area and comprising the same material, after the incubation step, to readily transfer at least one electron between the detectable species and one of the electrodes, thereby resulting in a Cottrell current;
d. measuring the Cottrell current; and
e. correlating the measured Cottrell current to the amount of analyte in the fluid sample. - View Dependent Claims (50)
-
-
51. A method for measuring the amount of a selected compound in a fluid sample, comprising:
-
providing a measuring cell having at least first and second electrodes of substantially the same size and comprising the same electrically conductive material, for contact with the fluid sample introduced into the cell, applying a potential to the electrodes to detect the presence of the fluid sample in the cell, placing the fluid sample into the cell, removing the potential to the electrode after the fluid sample is detected in the cell, selectively oxidizing the compound in the fluid sample with an oxidized electron acceptor to produce an oxidized form of the selected compound and a reduced electron acceptor, and re-applying a potential across the cell electrodes and measuring the resulting Cottrell current, said current being proportional to the concentration of the reduced electron acceptor and the selected compound in the fluid sample.
-
-
52. A method for measuring the amount of glucose in blood, comprising:
-
providing a measuring cell consisting of first and second electrodes for contact with blood introduced into the cell, said electrodes being of substantially the same size and comprising the same electrically conductive material, applying a potential across the electrodes, placing a volume of blood into the cell, removing the potential across the electrodes after the volume of blood is placed into the measuring cell, oxidizing the glucose in the blood with an oxidized electron acceptor in the presence of glucose oxidase to produce gluconic acid and a reduced electron acceptor, re-applying a potential across the measuring cell electrodes, and measuring the Cottrell current through the cell, the Cottrell current being proportional to the glucose concentration in the blood. - View Dependent Claims (53, 54, 55, 56, 57)
-
-
58. A device for analyzing an analyte, comprising:
-
a. a first electrical insulator;
b. a pair of electrodes consisting of working and second electrodes of substantially the same size, the electrodes being made of the same electrically conducting materials and being supported on the first electrical insulator;
c. a second electrical insulator, overlaying the first electrical insulator and the electrodes and including a cutout portion that exposes substantially equal surface areas of the working and second electrodes; and
d. a reagent substantially covering the exposed electrode surfaces in the cutout portion and comprising the oxidized form of a redox mediator, an enzyme, and a buffer, the oxidized form of the redox mediator being of sufficient type to receive at least one electron from a reaction involving enzyme, analyte, and oxidized form of the redox mediator and being in sufficient excess to insure that the diffusion limited electrooxidation of the redox mediator at the working electrode surface is the principle limiter of current flow through the device and to resist a shift in potential between the electrodes, the enzyme being of sufficient type and in sufficient amount to catalyze the reaction involving enzyme, analyte, and oxidized form of the redox mediator, and the buffer being unreactive with respect to the reduced and oxidized form of the redox mediator and being of sufficient type and in sufficient amount to provide and maintain a pH at which the enzyme catalyzes the reaction involving enzyme, analyte, and oxidized form of the redox mediator.
-
-
59. A reagent incorporated into a sample receiving portion of an electrochemical device that measures an analyte and that has a pair of electrodes consisting of working and second electrodes of substantially the same size, the electrodes being made of the same electrically conducting materials and having substantially equal surface areas in the sample receiving portion, comprising:
-
the oxidized form of a redox mediator, an enzyme, and a buffer, the oxidized form of the redox mediator being of sufficient type to receive at least one electron from a reaction involving enzyme, analyte, and oxidized form of the redox mediator and being in sufficient amount to insure that current produced by diffusion limited electrooxidation is limited by the oxidation of the reduced form of the redox mediator at the working electrode surface, the enzyme being of sufficient type and in sufficient amount to catalyze the reaction involving enzyme, analyte, and oxidized form of the redox mediator, and the buffer having a higher oxidation potential than the reduced form of the redox mediator and being of sufficient type and in sufficient amount to provide and maintain a pH at which the enzyme, analyte, and oxidized form of the redox mediator.
-
-
60. A reagent incorporated into a sample receiving portion of an electrochemical device that measures an analyte and that has a pair of electrodes consisting of working and second electrodes of substantially the same size, the electrodes being made of the same electrically conducting materials and having substantially equal surface areas in the sample receiving portion, comprising:
-
the reduced form of a redox mediator, an enzyme, and buffer, the reduced form of a redox mediator being of sufficient type to donate at least one electron from a reaction involving enzyme, analyte, and reduced form of the redox mediator and being in sufficient amount to insure that current produced by diffusion limited electroreduction is limited by the reduction of the oxidized form of the redox mediator at the working electrode surface, the enzyme being of sufficient type and in sufficient amount to catalyze the reaction involving enzyme, analyte, and the reduced form of the redox mediator, and the buffer having a lower reduction potential than the oxidized form of the redox mediator and being of sufficient type and in sufficient amount to provide and maintain a pH at which the enzyme catalyzes the reaction involving enzyme, analyte, and the reduced form of the redox mediator.
-
-
61. A method of determining the concentration of an analyte in a fluid, comprising the steps of:
-
a. contacting the fluid with a reagent that covers substantially equal surface areas of first and second electrodes and includes the oxidized form of a redox mediator, an enzyme, and a buffer, the oxidized form of the redox mediator being of sufficient type to receive at least one electron from a reaction involving enzyme, analyte, and oxidized form of the redox mediator and being in sufficient amount to insure that current produced by diffusion limited electrooxidation is limited by the oxidation of the reduced form of the redox mediator at the working electrode surface, the enzyme being of sufficient type and in sufficient amount to catalyze the reaction involving enzyme, analyte, and the oxidized form of the redox mediator, and the buffer having a higher oxidation potential than the reduced form of the redox mediator and being of sufficient type and in sufficient amount to provide and maintain a pH at which the enzyme catalyzes the reaction involving enzyme, analyte, and the oxidized form of the redox mediator;
b. allowing the reaction involving the enzyme, analyte, and the oxidized form of the redox mediator to go to completion;
c. subsequently applying a potential difference between the electrodes sufficient to cause diffusion limited electrooxidation of the reduced form of the redox mediator at the surface of the first electrode;
d. thereafter measuring the resulting diffusion limited current; and
e. correlating the current measurement to the concentration of the analyte in the fluid. - View Dependent Claims (62, 63, 64)
-
Specification