Mass/charge Ratio: Difference between revisions

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''m/z'' ratio.
''m/z'' ratio.


== [[Gold Book]] Entry ==
== [[Gold Book]] Entry ==
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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 C<sub>7</sub>H<sub>7</sub><sup>2+</sup>, ''m/z'' equals 45.5..
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 C<sub>7</sub>H<sub>7</sub><sup>2+</sup>, ''m/z'' equals 45.5..


== Proposed New Entry ==


The mass/charge ratio is a physical property that is measured by [[Mass Spectrometer | mass spectrometers]].
== References ==


The symbol for the physical quantity mass/charge is ''m/q''. The former ''[[m/z]]'' is based on a missconception and should no longer be used.
:[http://www.iupac.org/goldbook/Q04982.pdf gold book: quantity]


The SI unit of the physical quantity ''m/q'' is kilogram/coulomb ('''kg/C''').
:[http://www.iupac.org/goldbook/P04666.pdf gold book: physical quantity]
In [[Mass Spectrometry | mass spectrometry]] it is more common to use the [[Atomic Mass Unit]] '''u''' and the [http://www.iupac.org/goldbook/A00504.pdf atomic unit] for charge '''e''' which is equal to the [http://www.iupac.org/goldbook/E02032.pdf elementary charge].
This means the unit for mass/charge is:
: [''m/q''] = '''u'''/'''e'''


'''u''' is sometimes called [[Dalton]] ('''Da'''). '''u'''/'''e''' is sometimes called [[Thomson]] ('''Th'''). Hence, a [[Mass Spectrum | mass spectrum]] x-axis should be labeled as either of the below:
* ''m/q''  ('''u'''/'''e''')
* ''m/q''  ('''Da'''/'''e''')
* ''m/q''  ('''Th''')
== References ==
:[http://www.iupac.org/goldbook/Q04982.pdf gold book: quantity]
:[http://www.iupac.org/goldbook/P04666.pdf gold book: physical quantity]
:[http://www.iupac.org/goldbook/V06593.pdf gold book: value of a quantity]
:[http://www.iupac.org/goldbook/V06593.pdf gold book: value of a quantity]

Revision as of 16:56, 13 January 2005

Orange Book Entry

m/z ratio.


Gold Book Entry

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..


References

gold book: quantity
gold book: physical quantity
gold book: value of a quantity
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