MS3

**Semantic type:** Laboratory Procedure

**Definition:** Three mass spectrometers coupled in series. The targeted compound is selectively ionized, and its characteristic ions are separated from others in the mixture in the first mass spectrometer. The selected primary ions are then decomposed by collision in the second stage of mass spectrometry. The second stage products are fragmented again and the resulting products are run through the final mass analyzer.

**Synonyms:** - MS/MS/MS