Tannins, chromatography

J.P. Salminen, V. Ossipov, J. Loponen, E. Haukioja and K. Pihlaja, Characterisation of hydro lysable tannins from leaves of Batula pubescens by high performance liquid chromatography mass spectrometry, J. Chromatogr. A, 864, 283 291 (1999). 

Amao MB, Cano A, Alcolea JF and Acosta M. 2001b. Identification of hydrolysable tannins in the reaction zone of Eucalyptus nitens wood by high performance liquid chromatography-electrospray ionisation mass spectrometry. Phytochem Anal 12(2) 120—127. 

Crude GSE can be separated into distinct components from monomer-rich to oligomer- and polymer-rich fractions by solvent extraction followed by chromatography on Toyopearl resin. The pre-fractionation of the tannin crude extract by liquid-liquid extraction with ethyl acetate fractionates the monomers into the organic phase and improves the subsequent fractionation of oligomers and polymers on Toyopearl HW 40 resin. This fractionation technique is easy to operate and... 

Kolodziej H (1985) Fractionation of condensed tannins by counter current chromatography. 1 Chromatogr 318 85-93... 

Vivas, N. et al.. Differentiation of proanthocyanidin tannins from seeds, skins and stems of grapes Vitis vinifera) and heartwood of Quebracho (Schinopsis balansae) by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry and thioacidolysis/liquid chromatography/electro-spray ionization mass spectrometry. Anal Chim. Acta, 513, 247, 2004. 

Cheynier, V. et al.. Size separation of condensed tannins by normal-phase high-performance liquid chromatography. In Methods in Enzymology, Volume 299. Oxidants and Antioxidants. Part A. (ed. L. Packer), Academic Press, San Diego, 1999, p. 178. 

Fulcrand, H. et al.. Study of wine tannin oligomers by on-line liquid chromatography electrospray ionisation mass spectrometry. J. Agric. Food Chem. 47, 1023, 1999. 

New enological technologies aim to lower volatile acidity, enhance sugar content in must in cool climates and vice versa reduce the alcohol content of wines from hot climates, modify pH, cations, anions and acidity to achieve tartrate stability, complement traditional ageing in oak barrels with the use of small oak wood particles and most recently, extract phenolic compounds by a countercurrent chromatography process from wine to diminish or enrich tannins in red wines. 

With the first qualitative study on pigments accomplished by chromatography, it is apparent in retrospect that quantitative methods were needed. We describe the methods most applicable today although more work is needed, especially on tannins. 

Polymeric tannins have more complicated structures including esterified oligosaccharide chains for the hydrolyzable ones or further polymerization of the flavonoid units for condensed ones. Because of their diversity including small molecules and polymers, characterization of natural tannins is not simple. The first step in their characterization is isolation. This has been done using several procedures such as ultrafiltration and gel permeation chromatography [2]. 

Open-column chromatography with silica gel and alumina is not applicable to the fractionation of tanins because of their strong binding to these adsorbents, which induces extensive loss of tannins. Such losses do not occur with countercurrent chromatography, as it does not use a solid stationary phase. Such molecules are very polar, so butanol-based solvent systems can be used. Centrifugal partition chromatography is more adequate in this case, as compared to hydrodynamic CCC, because of the good retention of the stationary phase of a such solvent system. 

Hemes, P. J. and J. I. Hedges (2000) Determination of condensed tannin monomers in plant tissues, soils and sediments by capillary gas chromatography of acid depol5mrerization extracts. Analyt. Chem. 72, 5115-24. 

Even with condensed tannins, one finds that very mildly acidic conditions can cause anthocyanin groups to split off the polymer. Size exclusion chromatography of condensed tannins (Thompson et al., 1972) always reveals mixtures of oligomers. What is the true tannin molecule ... 

Hatano, T., T. Yoshida, and T. Okuda. 1988. Chromatography of tannins III. Multiple peaks in high-performance liquid diromatography of some hydrolyzable tannins. /. Chromatogr. 435 285-295. 

The pigmented wine tannin was isolated using a low-pressure adsorption chromatography technique used for tannin isolation (77). After this treatment, a deep red, pigmented isolate was obtained. The isolated material made up a significant amount of material in the wine (0.47 g/L). 

---