They gave (M–H) ion at m/z 609.14 and element composition of C27H29O16. In
their MS/MS spectra, after a 308 amu loss (one rhamnoside unit and
one glucoside or galactoside unit), higher abundance of (M–H) at
m/z 301.02 amu (assigned as quercetin) was observed. It could be
deduced that the sugar units were linked together and the sugar
chain was located at C3 position of quercetin skeleton.