Relationship between the Lipophilicity and Specific Hydrophobic Surface Are a of Non-Homologous Series

The lipophilicity and specific hydrophobic surface area of 43 synthetic dyes were determined on reversed-phase alumina layers using water-methanol mixtures as eluents. Carminic acid and hematoxylin remained on the start in each eluent system. The majority of dyes demonstrated regular retention behaviour, their retention decreased monotonously with increasing concentration of the organic modifier in the mobile phase. The retention of Rubin C increased with increasing concentration of methanol in the eluent (anomalous retention behaviour). Significant linear relationship was found between the lipophilicity and specific hydrophobic surface area of dyes indicating that, from the chromatographic point of view, they behave as a homologous series of compounds; however, their Chemical structures are markedly different