Polyparameter Linear Free Energy Models for Polyacrylate Fiber-Water Partition Coefficients to Evaluate the Efficiency of Solid-Phase Microextraction

The fiber water partition coefficient, K-fw, is decisive for performance of solid-phase microextraction (SPME) techniques in organic chemical analyses. In this study, polyacrylate (PA)-coated fiber was evaluated for its K-fw values toward diverse neutral organic compounds. Literature K-fw data were thoroughly evaluated, and additional K-fw values for 69 compounds were measured in phosphate-buffered saline (PBS) solution at 37 degrees C. These K-fw data, spanning over 6 orders of magnitude, were used to construct polypararneter linear free energy relationship (PP-LFER) models. The PP-LFER models fit well to the data with a standard deviation of 0.15-0.23 log units. Additional experiments indicated that the differences in temperature (25 vs 37 degrees C), electrolyte concentrations (pure water vs PBS), and conditioning methods (heat vs methanol) had only minor influences (<0.3 log units) on K-fw Using the established PP-LFERs, the SPME extraction efficiency of PA coating toward compounds of differing polarity was evaluated in comparison to poly(dimethylsiloxane) (PDMS) coating. PA exhibited higher extraction capacities for H-bond donor compounds (e.g., phenols, anilines, amides, and many drugs and pesticides) with the estimated K-fw, values being 1-4 log units higher than those of PDMS. Also, PA was shown to be more efficient than PDMS for hydrophobic aromatic compounds.