Talk:Nominal mass
From Mass Spec Terms
--Ionworker 12:22, 6 Jan 2005 (CST)
- Atomic weight should not be used because weight is a force and not a mass.
- Minimum nominal mass is a better name for the nominal mass of the lightest isotope.
- Isotope base mass would be more appropriate for the mass of the most abundant isotope.
Proposed Entry
The mass of an ion in atomic mass units rounded to the nearest integer.
- M = n Da = round(m)
The concept of nominal mass is useful because the mass of (small) molecules is always very close to their nominal mass. Many types of mass spectrometers do not have sufficient resolving power to distinguish molecules with the same nominal mass. For example CO and N2 both have the same nominal mass M = 28 and cannot be resolved by many mass spectrometers even though the accurate mass m is slightly different for the two molecules.
See also Accurate Mass, Average Mass, Atomic Mass Unit, Dalton.
Moved from front page.
- -- K. Murray 16:27, 18 Jan 2005 (CST)
