EFFECT OF SALTS ON THE HYDROPHOBICITY PARAMETERS OF SULFOSUCCINIC ACID-ESTERS STUDIED BY REVERSED-PHASE THIN-LAYER CHROMATOGRAPHY

The lipophilicity and specific hydrophobic surface area of 11 sulfosuc cinic acid esters have been determined by reversed-phase thin layer ch romatography in ion-free eluents and in eluents containing NaCl, KCl, MgCl2, and CaCl2. The strength and selectivity of the effect of salts were separated by use of the spectral mapping technique, Stepwise regr ession analysis was used to elucidate the relationship between the ret ention characteristics and the physicochemical parameters, Salts incre ased the retention of sulfosuccinic acid esters because of the salting -out effect and the suppression of the dissociation of the highly pola r acidic group, They also influenced the retention selectivity, the ef fect being greater for the specific hydrophobic surface area than for the hydrophobicity, The retention of the solutes was significantly dep endent on the molar refraction and the first and second coordinates of the two-dimensional nonlinear selectivity map depended on the calcula ted hydrophobicity and on the electron-withdrawing power of the substi tuent in the para position.