The objective of this article is to investigate some of the classical parameterizations used for modeling mass transfer between interstitial gas and cloud droplets for aqueous-phase models in Air Pollution Modeling [ Schwartz, 1986 ]. After an appropriate scaling of the initial model (a set of two coupled Partial Differential Equations), we apply the singular perturbation theory and some theoretical results of Reaction-Diffusion models with large diffusion coefficients. This justifies the use of classical parameterizations in a large range of parameters. Moreover, we propose a new parameterization of mass transfer, taking into account aqueous-phase diffusion limitations. This parameterization is based on a double-film model and may have an impact for some species, as it is illustrated with a simple box model