Figure 2.

Liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS). The experiment begins with a protein separation by liquid chromatography (LC) followed by ionization and mass spectrometry analysis. Triple quadrupole mass spectrometer comprises of three quadrupoles Q₁, Q₂, and Q₃. Quadrupoles Q₁ and Q₃ serve as mass filters. The middle quadrupole Q₂ functions as a collision cell. The specific precursor ions isolated by Q₁ and accumulated in Q₂ collide with neutral gas molecules, such as nitrogen generating the product ions. The product ions reach the third quadrupole assembly Q₃. The quadrupole Q₁ allows ions with a specific m/z ratio range to pass to the detector (D). P—pump; C –column; ES—electrospray, a liquid-to-aerosol converting device.