For a bare rotating disk electrode, the Levich equation can be used to determine the bulk diffusion coefficient (D) by plotting the diffusion limiting current (i

_{L}) against the square root of the rotation rate (ω).

i_{L}=0.62nFAD^{2/3} ν^{-1/6} C* ω^{1/2} (1)

The slope is made up of the known variables where n is the number of electrons in the redox reaction, F is Faraday’s constant, A is the electroactive area of the electrode, ν is the kinematic viscosity of the solution, and C* is the concentration of the analyte in the bulk.

The Dahms-Ruff equation can be used to determine the apparent diffusion coefficient of electrons (D_{E}) and the current due to this apparent diffusion (i_{E}).

D_{E}=D+kφ^{2} Cp* (π/4) (2)

i_{E}=(FAD_{E} Cp*)/δ_{m} (3)

where k is the rate constant of the redox reaction, φ is the average distance between the redox centers in the membrane, Cp* is the total amount of analyte in the membrane, and δm is the membrane thickness.

Equations 1 and 3 were combined to derive the Tedford equation in relation to the peak current (i_{p}).

i_{p}=0.62nFAD^{2/3} v^{-1/6} ω^{1/2} (C*-C_{m} )+(nFAD_{E} C_{m})/δ_{m} (4)

This equation can be used to determine the apparent diffusion coefficient of the electrons with the ferricyanide redox centers in the membrane. It can also be used to compare membranes with differing hydration times and possibly to study hydrating properties.