Published:Journal of Chromatographic Science,
ISSN 0021-9665Volume
38, Number 4, April 2000, pp. 145–150
Separation
and Tentative Identification of the Main Pigment Fraction of Raisins by Thin-Layer
Chromatography–Fourier Transform Infrared and High-Performance Liquid Chromatography–Ultraviolet
DetectionTibor
Cserháti and Esther Forgács Institute of Chemistry, Chemical Research Centre, Hungarian
Academy of Sciences, P.O. Box 17, 1525 Budapest, Hungary
Manuel Candeias, Louis Vilas-Boas, and Rosario
Bronze Estacao Nacional de Investigacao Agraria, Oeiras, Portugal
Isabell Spranger Estacao Vitivinicola Nacional, Dois Portos, Portugal
The soluble
color pigments of raisin are separated by reversed-phase thin-layer chromatography
(TLC), and the capacity of TLC–Fourier transform infrared (FTIR) with both
on-line and off-line coupling is assessed for the identification of the main
fraction. TLC has also been used as a pilot technique for the development of
a gradient elution method for the separation of pigments by high-performance
liquid chromatography (HPLC). On-line TLC–FTIR cannot be used for identification
because of the strong adsorbance of the stationary phase. Off-line TLC–FTIR
combined with the retention behavior of the main pigment fraction indicates
that it is a polymer, caramel-like compound composed of erythrose and fructose
monomers. Baseline separation of pigments is achieved by HPLC using TLC as a
pilot method.
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