Peculiarities of the Mass Spectrometric Detection of Anthocyanins in High-Performance Liquid Chromatography

The dependence of the degree of fragmentation of anthocyanin “molecular” ions on the cone voltage of a mass spectrometric electrospray ionization detector was studied. It was found that the voltage required for the fragmentation of 50% of original “molecular” ions, Ef(0.5), increased with the number of glycoside residues. The fragmentation of glycosides proceeds with the removal of the entire residue regardless of their structures. In the case of 3,5-diglycosides, two types of fragment ions formed due to the loss of glycosidic residues from different positions; the ratio of their peak intensities is reciprocal to the ratio of the masses of residues eliminated. The values of Ef(0.5) for monoglycosides (190 V), diglycosides (229 V), triglycosides (267 V), and for some acylated cyanidin-3,5-diglycosides are determined. These results were given for the gradient separation of anthocyanins by reversed-phase HPLC in aqueous acetonitrile containing 10 vol % of formic acid using quadrupole mass spectrometric detection.