259217.fig.004a
(a)
259217.fig.004b
(b)
Figure 4: Enlargements of negative ion nanospray product ion spectra of hesperetin at low (a) and high (b) collision energies. The competition between losses of CH3 and CH4 is clearly observed. At higher collision energy, the radical ion (m/z 286) has fragmented further to leave the quinonic ion (m/z 285) intact. The mechanism of formation of the two ions is shown in the inserts.