Figure 2. Typical chemical shift signal positions of polyphenol skeleton types in 1H NMR spectra based on plausible biosynthesis pathways in the 13C NMR spectrum. Each typical metabolite has a similar trend. Usually, tetramethylsilane (TMS) is used as an internal standard

From

Simplified Practical Identification of Polyphenol Types in Natural Dietaries Based on 1D and 2D Nuclear Magnetic Resonance

Azis Saifudin, Habibie Habibie, Muhammad Aswad, Yasuhiro Tezuka, Ken Tanaka

Journal of Food and Nutrition Research. 2023, 11(12), 742-751 doi:10.12691/jfnr-11-12-6