Kinetic analysis of isotope exchange from a cylinder

Isotopic exchange phenomena between a sample confined in a cylindrical container and a completely mixed solution of infinite size was analyzed. Fick's second law was used for the analysis of the transport of the labeled species from the cylindrical cell to the external solution. The model chosen for the analysis was that of two composite cylinders with different diffusion coefficients. Two cases were analyzed, where no mixing existed, and where complete mixing of the sample took place during the isotopic exchange. The analysis shows that the ratios of the diffusion coefficients and the thickness of the solution and membrane contribute to the number of observable exponential terms when the isotope remaining in the cylinder is plotted against time.