COMPARISON OF PERMEABILITY DATA FROM TRADITIONAL DIFFUSION CELLS AND ATR-FTIR SPECTROSCOPY .1. SYNTHETIC MEMBRANES

Diffusion cells and attenuated total reflectance Fourier transform inf ra-red (ATR-FTIR) spectroscopy have been used to monitor the permeatio n of a model compound, 4-cyanophenol (CP), across silicone membranes. CP permeation was measured across water saturated silicone membranes a nd untreated silicone membranes. In all cases the donor phase consiste d of a saturated aqueous solution of CP. The receptor phase used in th e diffusion cells was distilled water. After calibration of the ATR-FT IR system, it was found that the water saturated membranes yielded per meability co-efficients for CP identical to those found using diffusio n cells. In contrast, it was found that the permeability coefficient d etermined from the ATR-FTIR spectroscopy data for the untreated membra ne yielded a value almost two-fold greater than those obtained from bo th the diffusion cells and the ATR-FTIR spectrometer with the pre-satu rated membranes. It is likely that the untreated membrane used in the diffusion cell study contained a substantial amount of water before ap plication of the donor solution due to the inevitable uptake of the wa ter receptor medium. Therefore, as a result of the experimental techni ques and procedures used, the only membrane that was not hydrated to s ome degree before the donor phase was applied was the untreated one an alysed by ATR-FTIR spectroscopy. It has been demonstrated that, provid ed all initial conditions are effectively the same, there is a good co rrelation between permeability co-efficients measured using diffusion cells and ATR-FTIR spectroscopy. (C) 1997 Elsevier Science B.V.