Solubilization by cosolvents. Establishing useful constants for the log-linear model
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Updated: Aug 19, 2026

A New Straightforward Method for Lipophilicity (logP) Measurement using 19F NMR Spectroscopy
Published on: January 30, 2019
Jeffrey Millard1, F Alvarez-Núñez, S Yalkowsky
1Department of Pharmacy Practice and Science, College of Pharmacy, The University of Arizona, 1703 E. Mabel St., P.O. Box 210207, Tucson, AZ 85721-0207, USA.
Abstract:
The purpose of this study was to develop constants for the log-linear cosolvent model, thereby allowing accurate prediction of solubilization in the most common pharmaceutical cosolvents: propylene glycol, ethanol, polyethylene glycol 400, and glycerin. The solubilization power (sigma) of each cosolvent was determined for a large number of organic compounds from the slope of their log-solubility vs. cosolvent volume fraction plots. The solubilization data at room temperature were either experimentally determined or obtained from the literature. The slopes of the nearly linear relationship between solubilization power and solute hydrophobicity (logK(ow)) were obtained by linear regression analysis for each considered cosolvent. Thus, knowing or calculating a compound's partition coefficient is all that is needed to predict solubilization.
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