Paul ion trap

Ion trapping device that permits the ejection of ions with an m/z lower than a prescribed value and retention of those with higher mass. It depends on the application of radio frequency voltages between a ring electrode and two end-cap electrodes to confine the ion motion to a cyclic path described by an appropriate form of the Mathieu equation. The choice of these voltages determines the m/z below which ions are ejected.

The term cylindrical ion trap is deprecated.

A type of mass analyzer in which ions are confined in space by means of a three dimensional, rotationally symmetric quadrupolar electric field. Sorting of ions is performed by changing the field conditions appropriately to destabilize an ion of a particular m/z. The destabilized ion is then detected when it exits the trap and strikes a collection device, e.g. an electron multiplier or conversion dynode.