Four types of fluoroelastomer (VITON) membranes were tested for their resistivity toward dimethyl sulfoxide, dioxane, and toluene at 25, 45, and 60 degrees C, using a gravimetric method. Coefficients of diffusion and permeation were calculated from the sorption results. Analytical solutions of Fick’s equation as well as a numerical method were used to calculate the concentration profiles of liquids in the membrane materials at different penetration depths and exposure times. Activation parameters for diffusion, permeation, and sorption were obtained from the Arrhenius equation. These membrane materials were evaluated for their ability to serve as a barrier to solvent permeation in a composite membrane sampler for the analytical determination of isocyanates generated during spray-painting operations.