M/z

IUPAC RECOMMENDATIONS 2013
M/z
Deprecated: mass-to-charge ratio, Thomson. Abbreviation representing the dimensionless quantity formed by dividing the ratio of the mass of an ion to the unified atomic mass unit, by its charge number (regardless of sign). The abbreviation is written in italicized lowercase letters with no spaces. Note 1: Mass-to-charge ratio is deprecated. Mass-to-charge ratio has been used occasionally for the horizontal axis in a plot of a mass spectrum, although the quantity measured is not the ions mass divided by its electric charge (SI units kg C1). However, m/z is recommended as an abbreviation to represent the dimensionless quantity that is used almost universally as the independent variable in a mass spectrum. Note 2: The abbreviation m/z should not be used as a variable in a mathematical equation. Instead, the variables m (in kg) and q (in C) should be used to denote mass and charge. Note 3: The equal sign should not be used to denote a m/z value, for example, use m/z 100 and not m/z = 100. Note 4: The thomson (Th) unit is deprecated.
Related Term(s):
Reference(s): IUPAC. Analytical Division. Compendium of Analytical Nomenclature (the Orange Book). Definitive Rules, 1979. Compiled by J. Inczdy, T. Lengyel, A. M. Ure. Blackwell Scientific Publications, Oxford (1997). On-line corrected version: http://www.iupac.org /publications/analytical compendium (2000). IUPAC. Compendium of Chemical Terminology, 2nd ed. (the Gold Book). Compiled by A. D. McNaught and A.Wilkinson. Blackwell Scientific Publications, Oxford (1997). XML on-line corrected version: http://goldbook.iupac.org (2006-) created by M. Nic, J. Jirat, B. Kosata; updates compiled by A. Jenkins.
From Definitions of Terms Relating to Mass Spectrometry (IUPAC Recommendations 2013); DOI: 10.1351/PAC-REC-06-04-06 © IUPAC 2013.
Index of Recommended Terms

---

Orange Book

ORANGE BOOK DEFINITION IUPAC. Analytical Division. Compendium of Analytical Nomenclature (the Orange Book). Definitive Rules, 1979 (see also Orange Book 2023)
M/z
m/z ratio.
IUPAC 1997 Orange Book Chapter 12
Index of Orange Book Terms

Gold Book

GOLD BOOK DEFINITION IUPAC. Compendium of Chemical Terminology, 2nd ed. (the Gold Book). Compiled by A. D. McNaught and A.Wilkinson. Blackwell Scientific Publications, Oxford (1997).
M/z
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.
IUPAC Gold Book
Index of Gold Book Terms