Effects of substituted cyclodextrins on the separation of aromatic sulphonic acids by capillary zone electrophoresis

Effects of the addn. of various additives in the working electrolyte on the selectivity of capillary electrophoretic sepn. of naphthalenesulfonic acids used as intermediates in the prodn. of synthetic dyes were studied. Cyclodextrins form inclusion complexes with various compds. and are not only excellent chiral selectors, but were also successfully applied for sepns. of positional isomers. Me-b-cyclodextrin, heptakis(2,6-di-O-methyl)-b-cyclodextrin, heptakis(2,3,6-tri-O-methyl)-b-cyclodextrin, (2-hydroxypropyl)-b-cyclodextrin and (2-hydroxypropyl)-g-cyclodextrin were studied as isomeric selector additives and compared with unsubstituted b-cyclodextrin. In addn. to the size of the cyclodextrin cavity, the no. and type of the substituents in the cyclodextrin mols. strongly affect the sepn. of isomeric naphthalenesulfonic acids, but the effect of the substituted cyclodextrins on the sepn. selectivity is different for various types of sulfonic acids. Best sepns. of nonsubstituted naphthalenesulfonic acids were achieved in a borate buffer with Me-b-cyclodextrin, whereas the running buffer with nonsubstituted b-cyclodextrin provides superior sepn. of amino and hydroxynaphthalenesulfonic acids. [on SciFinder (R)]