mass-to-charge ratio, \(m_{\text{z}}\)

in mass spectrometry
https://doi.org/10.1351/goldbook.M03752
The abbreviation \(\frac{m}{z}\) is used to denote the dimensionless quantity formed by dividing the @M03726@ of an ion by its @C00993@. 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 \(\frac{m}{e}\) is, therefore, not recommended. Thus, for example, for the ion (C7H72+) , \(\frac{m}{z}\) equals 45.5.
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 [Terms] [Paper]