Yes. The choice of standard depends on the nature of the test material. Catechin hydrate has water molecules in it.

Good point, I M. Catechin mayhas been used components with high catechin content such fruits or tea or grape skin/seed extracts.

I. M., yes. Catechin can be used as a standard for flavonoid measurements in samples rich in catechin (examples --fruits, grape seed/skin extracts). Fruits are rich in anthocyanidins, which may exist as catechins in plant extracts (they lose color).

Yes,

definitely catechin hydrate could be used as standard for determination of flavonoids.

Respected Sir,

Yes, we can use catechin hydrate as standard for estimating flavonoids. Please go through the following article and it may help you.

Good Luck

Respected Sir,

Please go through this link

http://chromsci.oxfordjournals.org/content/early/2012/11/06/chromsci.bms180.full

Use of catechin as a standard to determine total flavonoids in fruit peels.

http://appleboost.com/pdfs/antioxidant-activity-2003-01-01-kelly-apple-peels-jaf.pdf

Antioxidant Activity of Apple Peels

KELLYWOLFE XIANZHONG WU RUI HAI LIU

Institute of Comparative and Environmental Toxicology and Department of Food Science, Cornell University, Ithaca, New York 14853-7201

I aggre with Phillip Morris. You should choice what method will used for determination of flavonoid in your sample at first and secondly you should determine the flavonoid that representative your sample. Because it can be influence the results. For example if you use spectrophotometric based method, the absorbance of (+)-catechin is  different with the other flavonoids, event with the (-)-epicatechin. The 1 ppm solution of (+)-catechin will gave a different absorbance with 1 ppm of (-)-epicatechin solution. If you inject 5 ul of 1 ppm (+)-catechin on an UV detector HPLC system, the peak area will different with the peak area of (-)-epicatechin in the same concentration.

The above pertinent answers are duly appreciated. Thank you!

I indicated in my first response (first answer), twenty five days ago that “…the choice of standard depends on the nature of the test material.", without going into details, implying that the choice of the method depended on the spectrum of major flavonoids in the test material in question. In many cases we know what the major flavonoids are in a test material, whether it is a fruit or skin extract.

Phenolics are highly concentrated in grape seeds and skins, not to leave wine. Gallic acid has been extensively used for total estimation of phenolic substances in wine and grape products by researchers at UC Davis, California for decades (at the dept. of enology and viticulture, using Folin's assay with modifications of Singleton Rossi thereof ). Gallic acid is a constituent of procyanidins ( proanthocyanidins, galloyl-catechins and polygalloyl-catechns) in wine and grape derived flavonoids. The above matrices contain procyanidins, whose constituent monomers are (+)-catechin and (-)-epicatechin, etc. Therefore, (+)-catechin has been employed as a standard for the quantitation of flavonoids in grape seed, grape skin, etc.

Apple peel contains substantive proanthocyanidins (polygalloyl procyanidins and catechin gallates); that is the reason that catechin has been used in determining flavonoid content of apple peels (see Kelly et al, above).

Can you please precise in which solvent we must dissolve Catechin standard for the estimation of total flavonoid in cereal extracts?