Determination of some structural features of procyanidins and related compounds by photodiode-array detection

In this work we have examined the use of a photodiode-array detector to identify unknown peaks corresponding to procyanidins and related compounds. The type of flavan-3-ol unit can be recognised from the absorption maximum (278.9 nm for catechin and epicatechin, and 270.6 nm for epigallocatechin), whereas the number of flavan-3-ol units does not affect this parameter, The min-max distance (distance between the minimum and the maximum in the original spectrum) decreases by 1.3 nm for each catechin or epicatechin unit. Gallates of flavan-3-ol can be detected by reference to the value of the convexity interval (distance between the inflection points before and after the maximum in the original spectrum).