Proanthocyanidins fragmentation

Procyanidin dimer, trimer, tetramer, and pentamers have molecular masses of 578, 866, 1154, and 1442, respectively. They can be easily identified using a mass spectrometer if [M H] m/z 577, 865, 1155, or 1441 are observed. Proanthocyanidins have three fragmentation... 

Figure 8.9 Fragmentation pathway of a proanthocyanidin dimer. The fragment mechanisms are RDA (retro-Diels-Alder), HRP (heterocyclic ring fission), and QM (quinone methide).

Figure 8.10 Sequencing the heterogeneous proanthocyanidin oligomers according to quinone methide fragment of inter-flavan bonds.

Figure 6.15. Positive fragmentation pathways of the monomer catechin retro-Diels-Alder fission (RDA), heterocychc ring fission (HRF), benzofuran-forming fission (BFF), and loss of water molecule. (Reprinted from Li and Deinzer, 2007, Tandem Mass Spectrometry for Sequencing Proanthocyanidins, Analytical Chemistry, 79, p. 1740, with permission from American Chemical Society.)...

The negative mass spectrum of Vitis vinifera permits identification of the ions related to proanthocyanidins, i.e., the monomer, dimer, trimer, tetramer, and pentamer (Table 2), as previously reported for positive ESI-MS equipped with a triple quadmpole [45]. The ion map of the same sample allows the detection of the different parent ions and their fragment products. For example, the ion m z 729 (dimer gallate) produces the fragments m/z 711 (loss of water). 

---