Karel UBIK-1, Irena MASTEROVÁ-2
1- Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the
Czech Republic, Flemingovo námesti 2, 166 10 Prague, The Czech Republic
2- Komenius University, Faculty of Pharmacy, Department of Farmacognosy and
Botany, Odbojárov 10, 832 32 Bratislava, The Slovak Republic
Intensive development in the field of metastabie ions including also collision activation has raised mass spectrometry to a qualitatively much higher level because it has initiated development of new types of scans (linked and combined scans) and both are real pre-conditions for the study of the structures of ions and molecules because they elucidate relationships among ions, giving fragmentation pathways (fragmentation maps).
Elucidation of the structures of the three related flavonoids isolated from Muscari racemosum was used to demonstrate a possibility of collision-induced dissociation followed by linked scans. The structure elucidation process includes low resolution measurement, high resolution measurement, calculation of doublebond equivalents, determination of the number of OH groups by replacing active hydrogens with deuterium using EtOD, collision-induced dissociation followed by linked scans of the both non-deuterated and deuterated compounds. Using only mass spectrometry it was possible to determine the complete structure of the two compounds as 5,7-dihydroxy-6-methoxy-3-(3',4'-dihydroxybenzyliden)chroman-4-one and 5,8-dihydroxy-7-methOxy-3-(3',4'-dihydroxybenzyliden)chroman-4-one. In the case of 5-methoxy-7-hydroxy-3-(3',4'-dihydroxybenzyliden)chroman-4-one only the positions of 5-OMe and 7-OH were necessary to determine using IR and NMR.