Investigation of proanthocyanidins by HPLC with electrospray ionization mass spectrometry

HPLC in combination with electrospray ionization mass spectrometric detecti on in the negative ion mode has been used successfully to investigate proan thocyanidins extracted from malt. Electrospray is a soft ionization techniq ue which offers the possibility of generating only pseudomolecular ions wit hout any fragmentation. The fragmentation pathways of dimeric and trimeric flavan-3-ols were elucidated by multiple stage experiments in an ion trap. It is possible to determine both the molecular weight and the sequence of t he monomeric units without preparative isolation of the compounds. As with other mass spectrometric techniques no differentiation between stereoisomer s is possible and no information about the position and stereochemistry of the interflavanoid linkage (4 --> 6 or 4 --> 8) is available. It seems to b e possible to apply the knowledge of the fragmentation of the analyzed comp ounds to higher oligomeric or polymeric flavanols.