Classical methods for extracting organic compounds from aqueous samples are generally based on either liquid/liquid extraction or liquid/solid extraction employing Solid Phase Extraction (SPE) disks or cartridges. More recently, methods have been introduced using non-extractable homogeneous sorptive polymers as extraction media. Solid Phase Micro Extraction (SPME), Stir-Bar Sorptive Extraction (SBSE), and Immobilized Liquid Extraction (ILE) have employed this technique. In this study, we evaluated the extractive properties of polydimethylsiloxane (PDMS), as well as diphenyl and trifluropropyl siloxanes and siloxanes blends using the ILE method. ILE shares many fundamental principles with traditional liquid/liquid extractions (LLE). In traditional LLE, a compound partitions between two immiscible liquid phases, usually an aqueous sample and an organic solvent, based on its affinity for each of the liquids. ILE separations are very similar; howere, the ‘organic solvent’ is instead a thin layer of polymer (immobilized liquid) that is coated on the surface of an ILE device. ILE Caps were used in this study. The septum of each ILE Cap is coated with a thin layer of non-extractable homogeneous sorptive polymer which acts as the extraction medium. A sample is directly exposed to the immobilized polymer to all analytes to partition from the sample into the polymer. Analytes which partition into the polymer (immobilized liquid) are desorbed into a small amount of GC solvent and may be analyzed immediately. This study investigates and evaluates extraction efficiency, enhancing or altering selectivity, solvent phenomena and effects, and discusses other characteristics associated with a variety of applications and extracting phases. Applications investigated in this analysis include the extractions of pesticides, PCBs, phenols and semivolatiles from water and more complex matrices like juice or whole fruit, as well as biological applications including the extraction of drug metabolites.
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