The development of a predictive method for the estimation of flux through polydimethylsiloxane membranes. III. Application to a series of substituted pyridines.

The steady-state flux of 35 substituted pyridine derivatives was determined in polydimethylsiloxane membranes using isopropyl alcohol as the receiver solvent. These diffusants constituted a diverse group of compounds possessing a wide range of hydrophobic, steric, and electronic characteristics. Various parameters representing these physicochemical properties such as cyclohexane-water fragmental constants, molar refractivity, Hammett's sigma constants, melting point, and mole fraction solubility were employed to develop empirical models capable of relating the flux to these characteristics of either the substituent on the pyridine ring or the compound itself.