page_title: Triple quadrupole mass spectrometer
section_title: Principle of operation
hierarchical_section_title: Triple quadrupole mass spectrometer / Principle of operation
caption_attribution_description: Figure 5 from "Apparatus For Separating Charged Particles Of Different Specific Charges" Patent number: 2939952; Filing date: Dec 21, 1954; Issue date: Jun 1960; Inventor: Paul et al.
context_page_description: A triple quadrupole mass spectrometer, is a tandem mass spectrometer consisting of two quadrupole mass analyzers in series, with a radio frequency –only quadrupole between them to act as a cell for collision-induced dissociation. This configuration is often abbreviated QqQ, here Q₁q₂Q₃.
context_section_description: Essentially the triple quadrupole mass spectrometer operates under the same principle as the single quadrupole mass analyzer. Each of the two mass filters (Q1 and Q3) contains four parallel, cylindrical metal rods. Both Q1 and Q3 are controlled by direct current (dc) and radio-frequency (rf) potentials, while the collision cell, q, is only subjected to RF potential. The RF potential associated with the collision cell (q) allows all ions that were selected for to pass through it. In some instruments, the normal quadrupole collision cell has been replaced by hexapole or octopole collision cells which improve efficiency.
  Unlike traditional MS techniques, MS/MS techniques allow for mass analysis to occur in a sequential manner in different regions of the instruments. The TQMS follows the tandem-in-space arrangement, due to ionization, primary mass selection, collision induced dissociation (CID), mass analysis of fragments produced during CID, and detection occurring in separate segments of the instrument. Sector instruments tend to surpass the TQMS in mass resolution and mass range. However, the triple quadrupole has the advantage of being cheaper, easy to operate and highly efficient. 
  Also, when operated in the selected reaction monitoring mode, the TQMS has superior detection sensitivity as well as quantification. The triple quadrupole allows the study of low-energy low-molecule reactions, which is useful when small molecules are being analyzed.
caption: Paul Patent 2939952 Fig5