In this paper, we report the results of a numerical study of how the model parameters for the kinetics of sorption based on Fick's law of diffusion coupled with an external convective mass transfer coefficient affect the D-optimal support points. The geometry studied was that of a slab of finite thickness but infinite width and length so that diffusion was characterized by a single dimension. Although a wide range of diffusivities characteristic of many foodstuffs were used, it was shown that the two support points for the design could be expressed in terms of just the dimensionless Biot number and the dimensionless Fourier modulus. (C) 2011 Elsevier Ltd. All rights reserved.