Fast and Simultaneous Determination of Gas Diffusivities and Solubilities in Liquids Employing a Thin-Layer Cell Coupled to a Mass Spectrometer, Part I: Setup and Methodology.

Transport properties and solubilities of volatile species in liquid solutions are of high interest in different chemical, biological, and physical systems. In this work, a new approach for determining the diffusivity and solubility of gases in liquids simultaneously is presented. The method presented relies on the diffusion of a volatile species through a thin, liquid layer and the subsequent detection of the species using a mass spectrometer. Evaluation of the time development of the resulting transient yields the diffusion coefficient, while the concentration of the species in the liquid layer can be calculated from the steady-state value of the flux into the mass spectrometer. Apart from the geometry of the thin layer and the calibration constant of the mass spectrometer no additional or external data are required. Experimental results of the temperature-dependent solubility and diffusivity of oxygen in dimethyl sulfoxide are presented in our companion paper Part II and serve as a proof of concept.