spectrum mass spectrum true The term is a misnomer because it is m/z rather than mass that is the independent variable in a mass spectrum. [IUPAC] A mass spectrum is a data distribution function that plots the relative abundances of ions forming a beam or other collection as a function of their m/z values. [IUPAC] mass spectra Pure Appl. Chem., Vol. 85, No. 7, pp. 1515–1609, 2013. http://dx.doi.org/10.1351/PAC-REC-06-04-06 mass spectrum data distribution function mass spectrometry result