Collision-induced dissociation

This article needs additional citations for verification. Please help improve this article by adding citations to reliable sources. Unsourced material may be challenged and removed. Find sources: "Collision-induced dissociation" – news · newspapers · books · scholar · JSTOR (September 2023) (Learn how and when to remove this message)

Collision-induced dissociation (CID), also known as collisionally activated dissociation (CAD), is a mass spectrometry technique to induce fragmentation of selected ions in the gas phase.^[1][2] The selected ions (typically molecular ions or protonated molecules) are usually accelerated by applying an electrical potential to increase the ion kinetic energy and then allowed to collide with neutral molecules (often helium, nitrogen, or argon). In the collision, some of the kinetic energy is converted into internal energy which results in bond breakage and the fragmentation of the molecular ion into smaller fragments. These fragment ions can then be analyzed by tandem mass spectrometry.

CID and the fragment ions produced by CID are used for several purposes. Partial or complete structural determination can be achieved. In some cases, identity can be established based on previous knowledge without determining structure. Another use is in simply achieving more sensitive and specific detection. By detecting a unique fragment ion, the precursor ion can be detected in the presence of other ions of the same m/z value (mass-to-charge ratio), reducing the background and increasing the limit of detection.