SEPARATION MECHANISM OF MICELLAR-ELECTROKINETIC CAPILLARY CHROMATOGRAPHY STUDIED BY QUANTITATIVE-STRUCTURE RETENTION RELATIONSHIP

The retention index in micellar electrokinetic capillary chromatograph y (MECC) has been analyzed by the quantitative-structure retention rel ationship. a good linear relationship between the retention index in t he SDS surfactant MECC and the logP and logk(w) values has been obtain ed; however, there is no such a linear relationship of retention index in the CTAB, DTAB surfactant MECC versus logP and logk(w) values. The retention index in the cationic and anionic surfactant MECC can be we ll correlated with the solvatochromic parameter; of solutes. The molec ular size and hydrogen bond interaction of solutes make the most impor tant contributions to the retention index. The former has almost no re lation with the surfactant properly, and the latter depends on the pro perty of the surfactant used. Different surfactant MECCs offer differe nt selectivities for the separation of polar compounds.