oh! i just found this. it doesnt require the use of a spectrophotometer, but i assume you need either that or a colorimeter or something of the sort, because it requires read wavelength.
http://72.14.209.104/search?q=cache:xZ4 ... cd=2&gl=us
i dont know if the link will work but it tested: "the phenolic and flavonoid contents and totalantioxidant capacities of cocoa, black tea, green tea, and redwine."
obviously i'm only doing tea, and not phenols. But this is the procedure for flavonoid content determination:
" Sample Preparation. The serving size of each beverage was defined as follows: commercial cocoa powder manufactured using a nonalka-lized process from Ghanaian cacao beans (7.3 g, 2 tablespoons in accordance with the manufacturer’s instructions) was dissolved in 200mL of distilled water (ddH2O) at 100 °C; commercial black tea (2 gbag) and green tea (2 g bag) were each extracted with 200 mL of ddH2Oat 100 °C for 2 min (according to the manufacturer’s instructions);and 140 mL of red wine (Merlot, California) as one serving size (14).The samples then were centrifuged in a Sorvall RC-5B refrigerated superspeed centrifuge (DuPont, Biomedical Products Department,Wilmington, DE) at 12000g using a GSA rotor for 5 min, and theresulting supernatants were used as the final samples. "
" Total Flavonoid Content. The total flavonoid concentration wasmeasured using a colorimetric assay developed by Zhishen et al. (8,9). Briefly, 1 mL of appropriately diluted sample was added to a 10mL volumetric flask containing 4 mL of ddH2O. At time zero, 0.3 mLof 5% NaNO2was added to each volumetric flask; at 5 min, 0.3 mL of10% AlCl3was added; at 6 min, 2 mL of 1 M NaOH was added. Eachreaction flask was then immediately diluted with 2.4 mL of ddH2Oand mixed. Absorbances of the mixtures upon the development of pinkcolor were determined at 510 nm relative to a prepared blank. The total flavonoid contents of the samples are expressed in milligrams per serving of epicatechin equivalents (ECE). All samples were prepared in five replications. "
it also measures antioxidant capacity with a procedure that is very complicated and involves the ABTS assay and something with vitamin C. But i think i just need flavonoids (?)
this just seems so much more simple. I dont know... second opinion please?
