Diffusivities of volatiles in concentrated solutions

Concentration profiles obtained by slicing a cylindrical gel were used to measure diffusion of volatiles in viscous aqueous dextrose solutions. The column length, slice thickness and diffusion time were optimized to maximize the repeatability of measurements, the results being very sensitive to small changes in variables. Coefficients of variation between 5 and 10% were obtained. In the presence of different concentrations of dextrose, the diffusivity of acetone decreased markedly as dextrose concentration increased. However, when the acetone concentration was varied within the range 0·6 to 13·7%, at a constant 50% (w/w) dextrose concentration, its diffusivity did not change significantly. The sliced gel system gave values of diffusivity in close agreement with those obtained by other techniques.