Derive an equation for the diffusion coefficient D in terms of V$1,$ V$2,$ C$1,$

C$2,$ C$10,$ C$20,$ k$,$ l$,$ A and t for a diffusion cell as illustrated in FigQ$3$

where the volume of the donor chamber is V$1$ and the receptor is V$2,$ t

is time, C$1$ is concentration of drug in donor chamber at time t$>0,$ C$2$ is

concentration of drug in receptor chamber at time t$>0,$ C$10$ is

concentration of drug in donor chamber at time t$=0,$ C$20$ is concentration

of drug in receptor chamber at time t$=0,$ k is the partition coefficient, l is

the membrane thickness, A is the cross sectional area of the membrane,

and t is time.

Fig Q$3$: Schematic diagram of a horizontal diffusion cell containing a polymer

membrane separating the donor and receptor reservoirs.