| Literature DB >> 11902913 |
Paul W Hartzfeld1, Rebecca Forkner, Mark D Hunter, Ann E Hagerman.
Abstract
A widely used method for analyzing hydrolyzable tannins afer reaction with KIO(3) has been modified to include a methanolysis step followed by oxidation with KIO(3). In the new method, hydrolyzable tannins (gallotannins and ellagitannins) are reacted at 85 degrees C for 20 h in methanol/sulfuric acid to quantitatively release methyl gallate. Dried plant samples can be methanolyzed under the same conditions to convert hydrolyzable tannins to methyl gallate. Oxidation of the methyl gallate by KIO(3) at pH 5.5, 30 degrees C, forms a chromophore with lambda(max) 525 nm, which is determined spectrophotometrically. The detection limit of the method is 1.5 microg of methyl gallate, and with plant samples, relative standard deviations of less than 3% were obtained.Entities:
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Year: 2002 PMID： 11902913 DOI： 10.1021/jf0111155
Source DB: PubMed Journal: J Agric Food Chem ISSN： 0021-8561 Impact factor: 5.279