ABSTRACT
Charged species such as ions, when passing through magnetic or electric fields (sectors), experience a force that deflects them from their original trajectory. This effect is utilized in magnetic-sector mass spectrometers to separate ions according to mass or, strictly, mass-to-charge ratio (m/z), the deflection being related to m/z and magnetic field strength (see Chapter 24). In a quadrupole instrument, only electric fields are used to separate ions according to mass. The ions are separated as they pass along the central axis of four parallel, equidistant rods (poles) that have DC and alternating (radio frequency, RF) voltages applied to them (Figure 25.1).
