CORRELATIONOF SOLVENT STRENGTH PARAMETER WITH TWO MOLECULAR DESCRIPTORS IN REVERSED-PHASE LIQUID CHROMATOGRAPHY

A new hydrophobicity index has been previously developed and reported (Rev. Roum. Chim., 2024, 69, 183). The new indexis based only on the solvent strength parameter (S) that describes the linear dependences (logk= logkw-S Phi) between the logarithm of the retention factor (k) and volume fraction of the organic modifier in mobile phase (Phi) in an HPLC separation. The correlations between the new hydrophobicity index and octanol-water partition constant (logK(ow)) were evaluated and reported in present study for a set of 20 solutes by using seven C18 HPLC columns and two organic modifiers, typically utilized in reversed-phase HPLC applications (acetonitrile and methanol). All the correlations were good, showing values above 0.85. Correlations between the extrapolated values of retention factor to zero percent of the organic modifier in mobile phase, logk(w),and log K-ow showed also good determination coefficients R-2, unlike an older hydrophobicity index based on the ratio between log( )k(w )and S, which was generally characterized by lower R(2 )than 0.8 for acetonitrile and 0.7 for methanol.