Determination of cyclodextrin content using periodate oxidation by capillary electrophoresis

A simple and general method suitable for the determination of cyclodextrin content in various matrices is described. The proposed method involves selective cleavage of C–C bonds with vicinal hydroxyl groups by means of periodate (Malaprade’s reaction). The amount of produced iodate is monitored by capillary electrophoresis. Optimized electrophoretic conditions (20 mM disodium tetraborate with 1 mM tetradecyltrimethylammonium bromide, direct UV detection λ=200 nm) ensure complete separation of periodate and iodate ions and sufficient sensitivity towards iodate. Under optimized reaction conditions (2-fold excess of periodate, temperature 70°C) reproducible quantitative results were obtained for α-, β- and γ-cyclodextrins as model samples. The proposed method was tested on a real sample of acrylamide — 2I-O-allyl-β-CD copolymer. The values of β-cyclodextrin content were compared with those obtained by reference NMR measurement and were found to be identical.