Nominal mass

From Mass Spectrometry Terms

PROVISIONAL RECOMMENDATION
Nominal mass
Mass of an ion or molecule calculated using the mass of the most abundant isotope of each element rounded to the nearest integer value and equivalent to the sum of the mass numbers of all constituent atoms.
Mass spectrometry terms project – included in submission Draft 0
Wikipedia link: Nominal mass

See also

• Mass

External links

• Base Peak Glossary

The mass of an ion containing the most abundant isotopes, calculated with nominal atomic weights. 

• Little Encyclopedia of MS

The nominal mass of an ion is calculated by simply adding the integer masses of the lightest isotopes of all elements contributing to the molecule, e.g. to calculate the nominal mass of CH₃Br you have to use the nominal masses of ¹²C, ¹H, and ⁷⁹Br to obtain M_nomi = 94 amu

• Shimadzu Mass Spectrometry Glossary

Same meaning as mass number (Nearest integer when expressing the mass of an atom in units that define ¹²C as 12. The number is approximately the sum of protons and neutrons in the atomic nucleus. In mass analysis the mass number is the sum of the masses of the atoms making up an ion or other particle (¹²C = 12, ¹H = 1, ¹⁶O = 16, ¹⁴N = 14...))

See additional comments on the Nominal mass discussion page.

See proposed definition on the Nominal mass discussion page.