ELECTRON-IMPACT MASS-SPECTRAL ANALYSIS OF FLAVONOIDS

Electron impact (EI) mass spectra were recorded for 43 flavones and flavonols, 7 isoflavones, 18 flavanones and dihydroflavonols, and 11 chalcones and dihydrochalcones. Chemical ionization (CH4) mass spectra were recorded for 9 flavonoid glycosides. The flavonoids gave significant fragments from the A and B rings that were classified according to the systems of Mabry and Markham (1975) and Grayer (1989). Often sufficient information from the fragmentations could be obtained to determine the molecular weight, the elemental formula, the substitution patterns in the A and B rings, and the class of flavonoid. Of the 79 flavonoids analyzed, 26 could not be located in the NIST database. With the flavonoid glycosides, CI (CH4) mass spectra gave significant fragments for the [M + 1]+ of the aglycon and the sugars. However, fragments from fission of the A and B rings were very weak.