Hyperbolic quadrupole (hyperquad)

Exhibit no. 129

The quadrupole is a type of mass analyzer, which separates ions based on the stability of their trajectories in the oscillating electric fields that are applied to four rods set parallel to each other. In a quadrupole assembly, rods opposite each other are connected electrically. AC and DC voltages are applied to the rods and these voltages are ramped during the scan. Voltages of the same amplitude and sign are applied to each rod pair, but the voltages applied to the other rod pair are opposite in sign. The frequency of the AC voltages is in the radio frequency range (“RF voltage”). The ratio of RF voltage to DC voltage determines the ability of the mass spectrometer to separate ions of different mass-to-charge ratios.