Abstract
The “Definitions of terms relating to mass spectrometry [IUPAC (International Union of Pure and Applied Chemistry) recommendations 2013]” define the term “MS/MS spectrum” as “a mass spectrum obtained using tandem mass spectrometry.” The semantic content of the term “MS/MS spectrum” is not only a product ion mass spectrum but also a precursor ion spectrum and a neutral loss spectrum. However, the term “MS/MS spectrum” is frequently used as a synonym of a product ion spectrum. An “MS/MS spectrum of the peptide angiotensin I” does not convey the same meaning as the “product ion spectrum of the peptide angiotensin I.”