Check https://bmcresnotes.biomedcentral.com/articles/10.1186/1756-0500-6-121

Also check https://www.hindawi.com/journals/ecam/2014/253875/

Our protocol is described in Article The Determination of Total Concentration and Activity of Ant...

Also check on this paper.

https://d-nb.info/1194231578/34

Thank you very much for the feedback you have sent in the discussion and for the download recommendation. Our experience shows that the FC method is very sensitive to the presence of other substances, such for example fruit acids. Therefore we are looking for alternative methods.

I hope that the topic of polyphenol determination will be interesting for many of us and that further discussions on this form will bring interesting thoughts.

Best regards and thank you again for your commitment.

Please look at the following below links which may help you in your analysis:

https://chembioagro.springeropen.com/track/pdf/10.1186/s40538-016-0077-1.pdf

https://www.scirp.org/pdf/ABC_2013121215561850.pdf

Thanks

Thank you Isam Eldin Hussein Elgailani for your suggestions. Especially second paper about Fe(III)/1,10-phenanthroline complexes is interesting according to comparing this with F-C methods. In some mentioned examples these differences are significant.

I have an additional question. Do any of you know the methods of determining the parts of tannins that have been oxidized during the storage of plant materials? This is especially important when storing plant extracts when the tannins are susceptible to oxidation with atmospheric oxygen.

Greetings to all participants and observers of this discussion.