Please i need help in interpreting my results. My sample is a plant extract already concentrated as a powder. I dissolved 20mg in 200ml acetone to get a 0.1mg/ml concentration while using 0.5ml aliquot for coorimetric analysis with 3ml butanol-HCL and 0.1ml ferric reagent. My absorbance is 0.113 (550nm). I dont seem to be able to take it off from there.
I suggest to perform folin-Denis method for quantitative estimation of Tannins using Tannic acid as reference standard
please see the following file
You must use some reference standard for comparing your result in equivalent weight.
There seem to be no standard for Condensed tannin analysis. I have seen procedures for total tannin which has a standard reference but CT does not. attached herewith is an FAO/IAEA manual which i have been using.
Some more reference
Makkar, H. P. S.; Gamble, G.; Becker, K. (1999). "Limitation of the butanol–hydrochloric acid–iron assay for bound condensed tannins". Food Chemistry 66: 129. doi:10.1016/S0308-8146(99)00043-6
Grabber J., Zeller, W.E., Mueller-Harvey, I. 2013. Acetone enhances the direct analysis of procyanidin- and prodelphinidin-based condensed tannins in Lotus species by the butanol-HCl-iron assay. J. Agric. Food Chem. doi:10.1021/jf304158m
One more
http://onlinelibrary.wiley.com/doi/10.1002/jsfa.2740580306/abstract?systemMessage=Wiley+Online+Library+will+be+disrupted+on+16th+May+from+12%3A00-14%3A00+BST+%2807%3A00-09%3A00+EDT%29+for+up+to+two+hours+for+essential+maintenance.++Apologies+for+the+inconvenience.
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