Thermo orbitrap fusion lumos mass spectrometer

CE experiments were performed using an Agilent 7100 (Agilent Technologies) coupled to a Thermo Orbitrap Fusion Lumos mass spectrometer (Thermo Fisher Scientific). The separation was conducted in a bare fused silica capillary with 50 μm ID and 60 cm length, initially conditioned with 5 M sodium hydroxide for 15 min, followed by water for 10 min and electrolyte for 30 min. The final electrolyte consisted of 10% acetic acid (v/v) with 10% (v/v) isopropanol. For separation, a potential of − 30 kV was applied to the capillary inlet. Samples were injected hydrodynamically with 100 mbar for 80 s. The sheath liquid consisted of isopropanol:water (50:50 v/v) with 0.5% (v/v) formic acid. A distance of 3.0 mm between the emitter tip and transfer capillary was chosen, giving the highest signal intensities. The Orbitrap mass spectrometer was operated in negative ion mode with 1200 V electrospray potential, full scan from 75 to 510 m/z, 30,000 resolving power, 64 ms accumulation time, 1E5 AGC target, 45% RF lens, and 4 microscans. MS/MS experiments were conducted with quadrupole isolation in a 1.6-Da window, fragmentation by high collision dissociation (stepped 15, 30, and 45%), and Orbitrap detection with first mass 50 m/z, AGC target 1E4, and 54 ms maximum injection time.