DETERMINATION OF IMPURITIES IN ALPHA-CYCLODEXTRIN BY GRADIENT HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHY WITH PULSED AMPEROMETRIC DETECTION

A gradient normal-phase high-performance liquid chromatography (NP-HPL C) method has been developed for the determination of impurities in al pha-cyclodextrin. The method is selective for six linear sugars and se veral late-eluting unidentified impurities, as well as for alpha-, bet a- and gamma-cyclodextrins. The HPLC system utilizes mobile phases con sisting of acetonitrile-water (A, 64:36; B, 35:65), a 5-mu m YMC Polya mine II column (250x4.6 mm I.D.), and pulsed amperometric detection. E xperiments were conducted to determine the optimal mobile phase concen trations, establish the precision of the method, and demonstrate linea rity and determine relative response factors for select sugars. The me thod was applied to select lots of commercial-grade alpha-cyclodextrin from two different manufacturers. The method is novel in that it offe rs gradient elution of strongly-retained impurities at ambient column temperatures and pulsed amperometric detection. (C) 1998 Elsevier Scie nce B.V.