Mechanistic study of the sorption properties of OASIS® HLB and its use in solid-phase extraction

The salvation parameter model is used to characterize the sorption properties of the porous polymer Oasis(R) HLB for solid-phase extraction with water and water-methanol mixtures as a sample solvent. Increasing solute size and electron lone pair interactions favor retention from water Oasis(R) HLB is not competitive with water for dipole-type and hydrogen-bond interactions, which result in lower analyte retention. The selectivity of Oasis(R) HLB is different to porous graphitic carbon (Hypercarb(R)), a conventional poly(styrene-divinyl benzene) porous polymer sorbent (PLRP-S 100) and two silica-based, octadecylsiloxane-bonded sorbents with a high and a low carbon loading, respectively Because of selectivity differences no single sorbent is ideal for the extraction of analytes possessing a wide range of polar interactions. Oasis(R) HLB is preferred for the extraction of low molecular mass and polar compounds, PLRP-S 100 for the extraction of higher molecular mass compounds of moderate polarity, and the silica-based octadecylsiloxane sorbent with a high carbon loading is the best compromise for the extraction of compounds that cover a wide polarity range. For methanol-water mixtures as a sample solvent PLRP-S 100 is the best general choice with Oasis(R) HLB preferred for the extraction of strong hydrogen-bond acids. Hypercarb(R) is shown to have favorable retention properties for solid-phase extraction with the except for its low surface area.