Characterization of Ascentis RP-Amide column: Lipophilicity measurement and linear solvation energy relationships |
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Authors: | Deborah Benhaim Eli Grushka |
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Institution: | Institute of Chemistry, The Hebrew University of Jerusalem, Edmund Safra Campus, Jerusalem 91904, Israel |
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Abstract: | This study investigates lipophilicity determination by chromatographic measurements using the polar embedded Ascentis RP-Amide stationary phase. As a new generation of amide-functionalized silica stationary phase, the Ascentis RP-Amide column is evaluated as a possible substitution to the n -octanol/water partitioning system for lipophilicity measurements. For this evaluation, extrapolated retention factors, log k′w, of a set of diverse compounds were determined using different methanol contents in the mobile phase. The use of n-octanol enriched mobile phase enhances the relationship between the slope (S ) of the extrapolation lines and the extrapolated log k′w (the intercept of the extrapolation), as well as the correlation between log P values and the extrapolated log k′w (1:1 correlation, r2 = 0.966). In addition, the use of isocratic retention factors, at 40% methanol in the mobile phase, provides a rapid tool for lipophilicity determination. The intermolecular interactions that contribute to the retention process in the Ascentis RP-Amide phase are characterized using the solvation parameter model of Abraham. The LSER system constants for the column are very similar to the LSER constants of the n-octanol/water extraction system. Tanaka radar plots are used for quick visual comparison of the system constants of the Ascentis RP-Amide column and the n-octanol/water extraction system. The results all indicate that the Ascentis RP-Amide stationary phase can provide reliable lipophilic data. |
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Keywords: | Chromatographic lipophilicity determination Linear solvation energy relationships Log P Log k&prime Octanol additive to mobile phase Polar embedded reversed-phase column |
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