RELATIONSHIP BETWEEN THE LIPOPHILICITY AND SPECIFIC HYDROPHOBIC SURFACE-AREA OF NON HOMOLOGOUS SERIES OF NONIONIC SURFACTANTS

The lipophilicity (R(M)), specific hydrophobic surface area and the re lative strength of interaction between trimethyl-beta-cyclodextrin and 39 nonionic surfactants having different hydrophobic moieties has bee n determined by charge-transfer thin-layer chromatography using methan ol as an organic modifier. R(M) values decreased linearly with increas ing concentration of methanol. The significant correlation between the R(M) value extrapolated to water and the specific hydrophobic surface area indicates that these surfactants can be considered from the chro matographic point of view as a homologous series of solutes independen tly of their structural inhomogeneity. Stepwise regression analysis su ggested that the length of alkyl chain in the hydrophobic moiety, the presence of sorbite and phenyl group in the surfactant molecule, and t he number of ethyleneoxide groups per molecule have the highest impact on their hydrophobic parameters. The relative strength of surfactant- cyclodextrin interaction significantly depended on the lipophilicity o f the surfactants, and on the presence of phenyl group and eater bonds in the surfactant molecule.