Use of thin-layer and over-pressured-layer chromatography to study the hydrophobicity of homologous s-triazines

Retention factors in pure water, log k(w), determined by linear extrapolation and by a numerical method based on Oscik's equation, and calculated values of log P have been compared as hydrophobicity indices for nine homologous s-triazines. In chromatographic studies thin-layer and over-pressured-layer chromatography were used. The effect of mobile phase pH on solute retention was investigated by use of different buffer-methanol mixtures. The effect of mobile and stationary phase properties on chromatographic behavior was also studied; three different organic modifiers (dioxane, acetonitrile, and tetrahydrofuran) and two stationary phases (RP-8 and RP-18) were used. Correlations of calculated log P values and log k(w) with carbon number, n(C) confirm the usefulness of chromatographic techniques for studying the hydrophobicity of organic compounds.