Analysis and characterisation of cyclodextrins and their inclusion complexes by affinity capillary electrophoresis

α-, β- and γ-cyclodextrins, which are composed of 6, 7 and 8 (1→4)-linked α-d-glucose units, are capable of forming complexes with molecules ranging from gases to proteins and other biopolymers. The physico-chemical properties of the guest molecules, such as their solubility, stability and reactivity can thereby be modified. For this reason they have found numerous applications in the agricultural, food, chemical and pharmaceutical industries. Cyclodextrins (CDs) have also been shown to be valuable as selectivity reagents for the resolution of structural, positional and stereo isomers in analytical chemistry and are important as media modifiers in the capillary electrophoretic separation of chiral biomolecules. CDs are produced from starch together with linear oligosaccharides by the extracellular microbial enzyme cyclodextrin glycosyltransferase (E.C. 2.4.1.19). Cyclodextrin glycosyltransferases are capable of producing cyclodextrins with six or more glucose units, mainly α-, β- and γ-CDs, as the major product. The analysis of the enzymatic reaction products is difficult due to the formation of a variety of both linear and cyclic oligosaccharides by cyclodextrin glycosyltransferases. Capillary electrophoresis provides a versatile and selective tool for their analysis in complex samples. Furthermore, capillary electrophoresis enables the characterisation of the inclusion complex forming properties of cyclodextrins using only minute amounts of sample. Copyright (C) 1999 Elsevier Science B.V.