Innovacera's quadrupole mass filter, abbreviated as quadrupole, is the core component of the quadrupole mass spectrometer. It is usually composed of four parallel cylindrical or hyperbolic metal rods. Two pairs of electrodes are applied: DC voltage (DC, U) and radio frequency voltage (RF, V·cos(ωt)). The quadrupole mass analyzer separates ions based on the stability of the ion trajectory in the oscillating electric field.