Some analytical applications of modified cyclodextrins

Abstract

There are studies dedicated to the molecular inclusion of biological substrates, like biogenic amines, amino acids, and peptides by cyclodextrins [1-3]. The interactions involved in cyclodextrin complexes (hydrogen bonding, van der Waals forces, release of conformational strain, change–transfer, electrostatic and hydrophobic interactions) are known to play an important role in pharmaceutical science, biochemistry, immunochemistry and also in analytical chemistry. Thus, cyclodextrins and their derivatives form inclusion complexes with aromatic amino acids or their oligopeptides, being well known that the aromatic amino acid residues are responsible for interaction of proteins/peptides. The analytical applications in extraction and transport processes of biological compounds such as amino acids by using modified cyclodextrins are presented. In order to outline the possibility of modified cyclodextrins acting as carriers through membrane, we have investigated some aspects of the solvent extraction and the transport through chloroform liquid membrane of some amino acid methylesters in the presence of picric acid or tropaeolin 00. The effects of physicochemical parameters involved in extraction and transport processes such as the structure of cyclodextrin, the nature of the anion used as counterion, and the structure of amino acid have been studied. Moreover the influence of the composition and the structure of the compounds under study upon the partition processes occurring in triphasic systems have been reported.