Examination of data relating to the thermodynamic and kinetic interactions between nonvolatile aqueous solutes and three ethylene–vinyl acetate copolymers

Abstract

Distribution coefficient (K s ) and diffusivity [diffusion coefficient (D)] values for 19 nonvolatile solutes were previously reported for three ethylene-vinyl acetate (EVA) copolymers. In this article, the interaction properties of these solutes are compared with their octanol/water partition coefficient (P o/w ) values. Adequate linear log/log correlations between K s and P o/w are obtained for all three copolymers, once the effect of the solution pH on solute speciation is taken into account. The resultant correlations are similar for all three copolymers, suggesting that they share a common interaction mechanism. Inverse correlations between log D and log P o/w are established for all three materials. Although the relationship between log D and log P o/w is linear for the EVA polymers, the scatter in the poly-(vinyl acetate) data is sufficiently large that a linear relationship cannot be unilaterally established. The utility of such a model in terms of assessing the potential interaction between a plastic container and its contained contents is demonstrated.

Evaluation of the Chemical Compatibility of Plastic Contact Materials and Pharmaceutical Products; Safety Considerations Related to Extractables and Leachables

“…Similarly, it is of some interest to be able to project how the accumulation of an extracted substance will be impacted by properties of the extracting medium (such as pH and polarity). Several recent publications have addressed the impact that extraction solution properties (e.g., pH and polarity) have on the leaching of organic substances from plastic materials 33, 38–41…”

Theoretical and Practical Considerations When Selecting Solvents for Use in Extractables Studies of Polymeric Contact Materials in Single-Use Systems Applied in the Production of Biopharmaceuticals

“…The accumulation of such compounds in water is of course limited by the partition coefficient, which is discussed later in the article. Octanol/water partition coefficients for some compounds are also available in the literature. , However, the accumulation of apolar organic compounds such as alkanes in aqueous solutions will not reach concentrations that could be detected in extractables studies, mimicking biopharmaceutical applications lasting up to several weeks or months. This is especially true in the case of multilayer film materials, as the layering may act to retard extractable migration …”