A simple diffusion model based on Fick's Law for diffusion was developed to simulate the evaporation/diffusion rate of small volumes of perfume liquid mixtures over time and distance. Thermodynamic UNIFAC model was used to predict the vapor–liquid equilibrium, since fragrance solutions were considered as non-ideal liquid mixtures. The diffusion model was applied to concentrated perfume mixtures but also to quaternary mixtures, considering the existence of a solvent matrix (ethanol). The PTD® methodology was applied to the study of the perfume evaporation and interpreted along with evaporation lines (EL) that traced the evaporation path of the perfume mixture.