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the normalized parameters using Eq. 13. From Fig. 5, it normalized current response J ,, for various values of it is clear that the value of the current increases when the normalized current reaches the steady-state value

Figure 5 the normalized parameters using Eq. 13. From Fig. 5, it normalized current response J ,, for various values of it is clear that the value of the current increases when the normalized current reaches the steady-state value

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We assume that the concentrations of all reactants and enzyme intermediates remain constant for all time. Also the concentration of total active enzyme [E, | and the reactants in the bulk electrode remain constant. We can consider that the diffusion of the reactants can be described by Fick’s second law and the enzymes are assumed to be uniformly dispersed throughout the matrix. The enzyme activity is not a function of position. The reaction/diffusion equations corresponding to the concentrations of substrate, oxidized mediator and oxygen within a matrix can be expressed as [14] We assume that the concentrations of all reactants and Eqs. 1-3 represent the general reaction scheme that occurs often at an electrode immobilized with an enzyme oxidase in the presence of two oxidants:
We assume that the concentrations of all reactants and enzyme intermediates remain constant for all time. Also the concentration of total active enzyme [E, | and the reactants in the bulk electrode remain constant. We can consider that the diffusion of the reactants can be described by Fick’s second law and the enzymes are assumed to be uniformly dispersed throughout the matrix. The enzyme activity is not a function of position. The reaction/diffusion equations corresponding to the concentrations of substrate, oxidized mediator and oxygen within a matrix can be expressed as [14] We assume that the concentrations of all reactants and Eqs. 1-3 represent the general reaction scheme that occurs often at an electrode immobilized with an enzyme oxidase in the presence of two oxidants:
FIG. 1 SCHEMATIC MODEL OF AN ENZYME-MEMBRANE ELECTRODES [12]
FIG. 1 SCHEMATIC MODEL OF AN ENZYME-MEMBRANE ELECTRODES [12]
Discussion Analytical Expressions of Concentrations of Substrate, Oxygen and Oxidized Mediator under Steady-state Condition
Discussion Analytical Expressions of Concentrations of Substrate, Oxygen and Oxidized Mediator under Steady-state Condition
Eqs. 10-12 represent the new analytical expression of concentrations of substrate, oxygen and oxidized mediator. dimensionless concentration profiles are described in
Eqs. 10-12 represent the new analytical expression of concentrations of substrate, oxygen and oxidized mediator. dimensionless concentration profiles are described in
diffusion coefficient of mediator is increased (Fig. 2c). SUBSTRATE Fg, (b) THE OXYGEN Fy , AND (c) THE OXIDIZED when the diffusion coefficients of substrate and
diffusion coefficient of mediator is increased (Fig. 2c). SUBSTRATE Fg, (b) THE OXYGEN Fy , AND (c) THE OXIDIZED when the diffusion coefficients of substrate and
values of the normalized parameters B,, B, and By. of the Thiele moduli De, D., and Ds, and some fixed
values of the normalized parameters B,, B, and By. of the Thiele moduli De, D., and Ds, and some fixed
FIG. 4 NORMALIZED CONCENTRATION PROFILES FOR (a) THE SUBSTRATE Fg , (b) THE OXYGEN Fo , AND (c) THE OXIDIZED
FIG. 4 NORMALIZED CONCENTRATION PROFILES FOR (a) THE SUBSTRATE Fg , (b) THE OXYGEN Fo , AND (c) THE OXIDIZED
FIG. 5 THE NORMALIZED CURRENT J ,, VERSUS THE THIELE
FIG. 5 THE NORMALIZED CURRENT J ,, VERSUS THE THIELE
Supposing the approximate solutions of Eqs. A3 — A5 have the form
Supposing the approximate solutions of Eqs. A3 — A5 have the form
oubstituting Eq. A6 into Eqs. A3 — Ad (respectively), and equate the terms with the identical powers of p, we obtain
oubstituting Eq. A6 into Eqs. A3 — Ad (respectively), and equate the terms with the identical powers of p, we obtain
TABLE. 1 COMPARISON OF NORMALIZED SUBSTRATE CONCENTRATION Fy WITH THE NUMERICAL RESULT FOR VARIOUS
TABLE. 1 COMPARISON OF NORMALIZED SUBSTRATE CONCENTRATION Fy WITH THE NUMERICAL RESULT FOR VARIOUS
TABLE. 2 COMPARISON OF NORMALIZED OXYGEN CONCENTRATION F, WITH THE NUMERICAL RESULTS FOR VARIOUS
TABLE. 2 COMPARISON OF NORMALIZED OXYGEN CONCENTRATION F, WITH THE NUMERICAL RESULTS FOR VARIOUS
TABLE. 3 COMPARISON OF NORMALIZED MEDIATOR CONCENTRATION F,, WITH THE NUMERICAL RESULT FOR VARIOUS Numerical values of parameters used in this work
TABLE. 3 COMPARISON OF NORMALIZED MEDIATOR CONCENTRATION F,, WITH THE NUMERICAL RESULT FOR VARIOUS Numerical values of parameters used in this work
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