Thursday, April 9, 2015

Noyes-Whitney Equation:



Noyes-Whitney Equation:

Noyes & Whitney described the quantitative analysis of the amount of drug dissolved from a solid particle as a function of time.
Derivation from Fick’s law of diffusion:


                 


Equation:

                                    Dc /S
                   dc/dt=                  (Cs – C)
                                      h

Where,
c = amount of drug dissolved (mg) in time t(s).
Dc = diffusion coefficient of the drug (cm2s-1).
S = surface area of drug (cm2)
h = thickness of the diffusion layer liquid film (cm).
Cs = Saturation solubility of the drug (mg.cm-3).
C = concentration of drug in bulk solution (mg.cm-3).