Determination of the lipophilicity of some anti-hypoxia drugs: Comparison of TLC and HPLC methods

Effect of salt concentration and pH on the hydrophobicity parameters of surfactants studied by TLC and spectral mapping technique

The lipophilicity and specific hydrophobic area of 56 surfactants having different hydrophobic moiety and different length of ethylene oxide chain were determined by reversed-phase thin-layer chromatography and the strength and selectivity of the effect of sodium chloride and pH on the hydrophobicity parameters was elucidated using spectral mapping technique followed by two-dimensional nonlinear mapping. In each instance significant linear correlations were found between the lipophilicity and specific hydrophobic surface area of surfactants suggesting that from a chromatographic point of view they behave as a homologous series of solutes. It was established that the strength of the effect of both salt concentration and pH is relatively low and the selectivity of their influence on the hydrophobicity parameters is markedly different.

Lipophilicity determination of non-homologous series of nonionic surfactants by means of reversed-phase thin-layer chromatography

The lipophilicity and specific hydrophobic surface area of 22 nonionic surfactants having different hydrophobic moieties have been determined by reversed-phase thin-layer chromatography using methanol as an organic modifier. RM values decreased linearly with increasing concentration of methanol. Both the lipophilicity and specific hydrophobic surface area of the surfactants decreased with increasing numbers of ethylene oxide groups per molecule. The significant correlation between the RM0 value and the specific hydrophobic surface area indicates that these surfactants can be considered as a homologous series of solutes independently of their structural inhomogeneity. Stepwise regression analysis suggested that the hydrophobic moieties are not entirely solvated and they are in a folded state in the eluents.