A Consideration of the Impact of Solution Composition on the Accumulation of Organic Substances Leached from Plastics Used in Container/Closure Systems

Abstract

A multi-layered, laminated plastic material, similar to those used in flexible intravenous solution containers, was loaded to contain known amounts of 15 model compounds whose partitioning behaviors were previously established. The loaded material was extracted with eight different extracting solutions including water (ambient pH); pH 3, 4, 5, and 7 aqueous buffers; and 20%, 40%, and 60% (v/v) ethanol/water mixtures (pH 3). The accumulation of model compounds in the extracting solutions was measured and related to compound and solution properties. The loading of the plastic material occurred in a manner that was consistent with the partitioning behavior of the model compounds. The accumulation of the model compounds in the extracting solution was influenced by the compound's partitioning behavior, total available pool in the plastic, and the extracting solvent's polarity. The accumulation of the acidic compounds in the extracting solutions was predictably affected by extraction solution pH. The accumulation conditions used in this study were not sufficient to reach equilibrium between the extracted material and the extracting solution. Such an outcome allowed for a consideration of the impact of a compound's migration characteristics on its accumulation levels. The model compounds could be grouped as “polar” or “non-polar” on the basis of the relationship between their measured accumulation level and their calculated equilibrium accumulation level.