J. Mass Spectrom. Soc. Jpn. Vol. 56, No. 1, Comments on the Usage of the Terms Accurate Mass and Exact Mass 1, 2. Ken-ichi YDH=>CD 1, 2

Letter from the Editor-in-Chief

Letter from the Editor-in-Chief

13

Accurate Mass

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Exact Mass

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Comments on the Usage of the Terms “Accurate Mass”

and “Exact Mass”

Ken-ichi Y

DH=>CD

1 _{Biosignal Research Center,}

Organization of Advanced Science and Technology, Kobe University, Kobe, JAPAN 2 _{! Editor-in-chief}

The terms “accurate mass” and “exact mass” are not synonymous in mass spectrometry. Accurate mass refers to the mass value of an ion or radical determined experimentally by mass spectrometry. On the other hand, exact mass refers to the mass value of a single ion, radical, or molecule calculated by summing the mass values of individual isotopes. To avoid confusion, “measured accurate mass” and “calculated exact mass” should be used in place of “accurate mass” and “exact mass,” respectively.

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1) K. K. Murray, R. K. Boyd, M. N. Eberlin, G. J. Langley, L. Li, and Y. Naito, “Standard Definitions of Terms Relating to Mass Spectrometry (IUPAC Recommendations 2006),” Draft, 31 Aug 2006; URL:_ºhttp://www.iupac.org/reports/provisional/ abstract06/murrayῌprs.pdf».

2) O. D. Sparkman, “Mass Spectrometry Desk Reference, 2nd Edition,” Global View Publishing, Pittsburgh (2006), p. 60.