Analytical characterizations of purities of alkyl- and arylamino derivatives of beta-cyclodextrin by capillary zone electrophoresis with conductivitydetection

The use of capillary zone electrophoresis (CZE) with conductivity detection to analytical characterizations of 6(I)-deoxy-6(I)-alkyl- and 6(I)-deoxp-6 (I)-aryl-amino-beta-cyclodextrins (R-A-beta-CDs) was investigated. Cationic compositions of a group of nine R-A-beta-CDs prepared for the use in chira l capillary electrophoresis separations were evaluated in this context. Dif ferences in the actual ionic mobilities and in host-guest complexation prop erties of the cationic constituents present in these beta-CD preparations w ere used in the CZE separations. The CZE migration data obtained in the ele ctrolyte systems implementing these separation mechanisms and a relationshi p between these data and estimated molecular mass/effective charge number r atios of the derivatives of different degrees of substitution made possible tentative identifications of the cationic impurities present in the studie d preparations. Of these, di- and triamino-beta-CD derivatives can be assum ed to be of a key relevance as they may adversely influence complexing prop erties of the R-A-beta-CD preparations. The monoaminoderivatives (the major constituents) migrated under the separating conditions providing their ful l ionizations with identical effective mobilities. Such migration propertie s gave a possibility for quantitative estimations of their actual contents in the preparations using a relationship between the molar response of the conductivity detector (the slope of the calibration line) and the effective mobilities of the CZE zone forming constituent.