What Is the Function of the Collision Gas (CAD) on QTRAP® System Instruments?

For research use only. Not for use in diagnostic procedures.

Answer

The Collision Gas (CAD) is one of the compound-dependent parameters set by the user on the QTRAP® LC/MS/MS system instruments.

The CAD parameter controls the collision gas pressure in the collision cell during Q3 MS, MS/MS-type, and linear ion trap (LIT) scans.

For Q3 MS scans, the collision gas helps to focus the ions as they pass through the collision cell; by default, this parameter is in fixed mode.

For MS/MS-type scans, the collision gas acts to fragment the precursor (parent) ions. When parent ions collide with collision gas molecules, they dissociate into fragment ions.

During LIT scans, the collision gas helps focus and trap ions in the LIT.