USE OF HPLC SEPARATION PHOTODIODE ARRAY DETECTION FOR CHARACTERIZATION OF ANTHOCYANINS

A systematic procedure for separation and characterization of anthocyanins is described. Separation of pigments was achieved by high-performance liquid chromatography (HPLC) on a polymer reversed-phase column. Methods for preparation of an anthocyanin isolate free of other interfering phenolics were developed. Photodiode array detection was employed to determine the UV-visible spectral characteristics of the pigments. Derivatives of delphinidin (delphinidin, petunidin, malvidin) can be distinguished from derivatives of cyanidin (cyanidin, peonidin), which in turn can be distinguished from pelargonidin derivatives on the basis of their different UV-visible spectra. Acylation with cinnamic acids and differentiation between 3- and 3,5-glycosidation can also be determined from the UV-visible spectrum. Auxiliary sample preparation techniques useful for pigment characterization included alkaline hydrolysis of the anthocyanins for determination of acylation. Anthocyanins not containing an o-diphenolic system can be enriched on a C18reversed-phase cartridge by elution with alkaline borate buffer. With a combination of these techniques, peak assignments for the anthocyanins from sources whose anthocyanin composition is known can be readily made. © 1990, American Chemical Society. All rights reserved.