A REVIEW: SEPARATION AND CHEMICAL PROPERTIES OF ANTHOCYANINS USED FOR THEIR QUALITATIVE AND QUANTITATIVE ANALYSIS

Methods of analysis for naturally occurring anthocyanins are described. The large number of chemical groups which may bind to the flavylium molecule has contributed to a large variation in structure, making the qualitative analysis of anthocyanins difficult. Qualitative analysis has generally involved preliminary solvent extraction followed by chromatographic separation and purification of pigments. Individual anthocyanins are then characterized by their chromatographic mobility, absorption spectra, and by means of controlled hydrolysis and oxidation tests. Quantitative analysis of anthocyanins may be carried out using either differential or subtractive spectral methods. The validity of results obtained by either of these methods is dependent on the presence or absence of interfering substances within the samples. Where the quantification of individual anthocyanins is desired, their separation from a mixture, normally by means of column chromatography, is first necessary. High resolution of microgram quantities of anthocyanin without the need for extensive sample purification prior to analysis has led to an increase in the use of HPLC techniques for quantitative work.