Triple quadrupole mass spectrometer

Waters Quattro II triple quadropole mass spectrometer (center). This photo was taken in the old mass spec facility in Whitmore Lab of Pennsylvania State University.
Quadrupole from a Waters TQ-S triple quadrupole mass spectrometer

A triple quadrupole mass spectrometer (TQMS), is a tandem mass spectrometer consisting of two quadrupole mass analyzers in series, with a (non-mass-resolving) radio frequency (RF)–only quadrupole between them to act as a cell for collision-induced dissociation. This configuration is often abbreviated QqQ, here Q1q2Q3.