... brown powder Grape seed extract polyphenols: 1. 95% by UV, folin assay 2. 95% polyphenols with 15% phenolic monomers including 3 ... . Atechin, epicatechin, ECG, etc. By UV, Folin Assay and HPLC. 90% by UV, folin assay 4. 90% polyphenols with 10% phenolic ... monomers including 5. atechin, epicatechin, ECG, etc. By UV, Folin Assay and HPLC Grape Skin Extract1. Anthocyanidins(OPC) 5%, 25 ...