Talk:M/q: Difference between revisions

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{{Sugdef|m/q|


m/q is the symbol for a physical quantity [[Mass/charge Ratio|mass/charge]] which is measured by [[Mass Spectrometer|mass spectrometers]].
The former ''[[m/z]]'' is based on a [[Talk:Mass/Charge Ratio (Th, never use Da, no units?. An ion of m/z or an ion at m/z?)|missconception]] and should no longer be used.
The SI unit of the physical quantity ''m/q'' is kilogram/coulomb ('''kg/C''').
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'''
For simplicity, '''u''' is better called [[Dalton]] ('''Da''') and '''e''' is called [[Millikan]] ('''Mi'''). 
'''u'''/'''e''' is sometimes called [[Thomson]] ('''Th''').
Therefore
: [''m/q''] = '''u'''/'''e''' = '''Da'''/'''Mi''' = '''Th''' 
Hence, a [[Mass Spectrum | mass spectrum]] x-axis should be labeled as either of the below:
* ''m/q''  ('''u'''/'''e''')
* ''m/q''  ('''Da'''/'''Mi''')
* ''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]
}}

Latest revision as of 22:11, 17 June 2013