Electrochemical cell
First Claim
1. A method for determining the concentration of a reduced or oxidized form of a redox species, said method comprising the steps of:
- (1) providing an electrochemical cell comprising a working electrode and a counter electrode, (2) applying an electric potential difference between the electrodes, (3) selecting the potential of the working, electrode such that the rate of electro-oxidation of the reduced form or electro-reduction of the oxidized form of the species is diffusion controlled, (4) selecting the spacing between the working electrode and the counter electrode so that reaction products from the counter electrode arrive at the working electrode, (5) determining current as a function of time after application of the potential and prior to achievement of a steady state, (6) estimating the magnitude of the steady state current, and (7) obtaining from the change in current with time and the magnitude of the steady state current, a value indicative of the diffusion coefficient and/or of the concentration of the reduced form or the oxidized fonn of the species.
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Abstract
A method for determining the concentration of a reduced (or oxidised) form of a redox species in an electrochemical cell of the kind comprising a working electrode and a counter electrode spaced from the working electrode by a predetermined distance, said method comprising the steps of: (1) applying an electric potential difference between the electrodes; (2) selecting the potential of the working electrode such that the rate of electro-oxidation of the reduced form (or electro-reduction of the oxidised form) of the species is diffusion controlled, (3) selecting the spacing between the working electrode and the counter electrode so that reaction products from the counter electrode arrive at the working electrode; (4) determining current as a function of time after application of the potential and prior to achievement of a steady state; (5) estimating the magnitude of the steady state current, and (6) obtaining from the change in current with time and the magnitude of the steady state current, a value indicative of the diffusion coefficient and/or of the concentration of the reduced form (or the oxidised form) of the species. Also disclosed is an apparatus for determining the concentration of a redox species in an electrochemical cell comprising: an electrochemical cell having a working electrode and a counter (or counter/reference) electrode, means for applying and electric potential difference between said electrodes, means for measuring the change in current with time, and characterised in that the working electrode is spaced from the counter electrode by less than 500 μm.
439 Citations
108 Claims
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1. A method for determining the concentration of a reduced or oxidized form of a redox species, said method comprising the steps of:
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(1) providing an electrochemical cell comprising a working electrode and a counter electrode, (2) applying an electric potential difference between the electrodes, (3) selecting the potential of the working, electrode such that the rate of electro-oxidation of the reduced form or electro-reduction of the oxidized form of the species is diffusion controlled, (4) selecting the spacing between the working electrode and the counter electrode so that reaction products from the counter electrode arrive at the working electrode, (5) determining current as a function of time after application of the potential and prior to achievement of a steady state, (6) estimating the magnitude of the steady state current, and (7) obtaining from the change in current with time and the magnitude of the steady state current, a value indicative of the diffusion coefficient and/or of the concentration of the reduced form or the oxidized fonn of the species. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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- 12. Apparatus comprising a porous membrane, a working electrode on one side of the membrane, a counter electrode on the other side of the membrane, said electrodes together with a zone of the membrane therebetween defining an electrochemical cell, and wherein the membrane extends laterally from the cell to a sample deposition area spaced apart from the cell zone by a distance greater than the thickness of the membrane, wherein the distamce is sufficient so that when blood is placed on the sample deposition area, a plasma front diffuses laterally towards the cell zone in advance of the red cells, filling the cell area with plasma substantially free of hematocrit.
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23. Apparatus for determining the concentration of a redox species in an electrochemical cell comprising:
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a hollow electrochemical cell having a working electrode and a counter or counter/reference electrode, means for applying an electric potential difference between said electrodes, means for measuring the change in current with time, and characterised in that the working electrode is spaced from the counter electrode by less than 500 μ
m.- View Dependent Claims (24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64)
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- 65. A hollow electrochemical cell comprising a working electrode, a counter electrode and an opening for admitting an analyte to the cell, the working electrode being spaced from the counter electrode by less than 500 μ
Specification