Negative and positive ionization mode was used in the range
m/z 100–1000 at a scan speed of 13,000 Da/s. High purity nitrogen
(N2) was used both as drying gas (10.0 mL/min) and as a nebulizing
gas at a pressure of 50 psi. The nebulizer temperature was
set at 365 ◦C and capillary voltage was +400 V. Helium (He, Ultrahigh-
purity) was used as collision gas at a pressure of 1×10−5 mbar
and the collision energy was fixed at 40 V. MSn data were acquired
in auto MSn mode(isolation width of 4.0 m/z). For MSn analysis,
the mass spectrometer scanned from 10 to 1000 m/z with fragmentation
amplitude of 1.0V (MSn up to MS4) and two precursor
ions.