STUDY OF THE INFLUENCE OF ELECTRONIC EFFECTS ON THE RETENTION OF SUBSTITUTED N-BENZYLIDENEANILINES IN NORMAL-PHASE LIQUID-CHROMATOGRAPHY

A series of 72 substituted N-benzylideneanilines (NBA) has been studie d by normal-phase liquid chromatography by use of an experimental desi gn based on variation of the composition of mobile phases prepared fro m heptane and three modifiers, tetrahydrofuran, 1-octanol and ethyl ac etate, for each of which the specific interactions are different. Seve n mobile phases were defined in the experimental design. The chromatog raphic data obtained are used to discuss the behavior of NEA by applic ation of complementary chemometric methods - hierarchical ascending cl assification (HAC) and correspondence factor analysis (CFA). Although solute polarity has the greatest effect on retention, construction of HAC and CFA plots shows that solute behavior is also influenced by sec ond-order electronic effects arising as a result of specific interacti ons between the solutes and the different modifier solvents. A quantit ative structure-retention relationship has been established between Ha mmett's constants and the solutes projection on the first factorial ax is of CFA.