Term: mass-to-charge ratio, \(m_{\text{z}}\)
https://doi.org/10.1351/goldbook.M03752

Definition:
The abbreviation m/z is used to denote the dimensionless quantity formed by dividing the mass number of an ion by its charge number. It has long been called the mass-to-charge ratio although m is not the ionic mass nor is z a multiple or the elementary (electronic) charge, e. The abbreviation m e is, therefore, not recommended. Thus, for example, for the ion (C7H72+) , m/z equals 45.5.

Related Terms:
1) mass number (http://doi.org/10.1351/goldbook.M03726).
2) charge number (http://doi.org/10.1351/goldbook.C00993).

Source: PAC, 1991, 63, 1541. 'Recommendations for nomenclature and symbolism for mass spectroscopy (including an appendix of terms used in vacuum technology). (Recommendations 1991)' on page 1544 (https://doi.org/10.1351/pac199163101541)

Citation: 'mass-to-charge ratio, \(m_{\text{z}}\)' in IUPAC Compendium of Chemical Terminology, 5th ed. International Union of Pure and Applied Chemistry; 2025. Online version 5.0.0, 2025. https://doi.org/10.1351/goldbook.M03752

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