Analytical Sciences
Online ISSN : 1348-2246
Print ISSN : 0910-6340
ISSN-L : 0910-6340
Original Papers
Exploratory Analysis of Simultaneous Degradation of Anthocyanins in the Calyces of Flowers of the Hibiscus sabdariffa Species by PARAFAC Model
Paulo H. MARÇOMaria Alice B. LEVIIeda S. SCARMINIORonei J. POPPIMarcello G. TREVISAN
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2005 Volume 21 Issue 12 Pages 1523-1527

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Abstract

A three-way resolution method based on PARAFAC model was applied for the UV-Vis spectra to study the simultaneous degradation of anthocyanins extracted from fresh calyces of flowers of the Hibiscus sabdariffa. This methodology was used to resolve a chemical system, for which there was no a priori information about the composition or the pure spectra, a so-called black system. In the pH range from 1 to 13, seven species were identified: flavylium cation, carbinol, quinoidal base, E- and Z-chalcones and E- and Z-ionized chalcones. The concentration changes were determined as functions of pH at different wavelengths. The pK values for the acidity constants as well as tautomeric constant were estimated as 2.70, 3.54 and 0.14, respectively. The spectral profiles recovered by the chemometric methods are in excellent agreement with bands of experimental spectra reported in the literature for the species measured at specific pH values.

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© 2005 by The Japan Society for Analytical Chemistry
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