Preferred Label : molecular ion;
Detailed label : molecular ion in mass spectrometry;
IUPAC definition : An ion formed by the removal from (positive ions) or addition to (negative ions) a
molecule of one or more electrons without fragmentation of the molecular structure.
The mass of this ion corresponds to the sum of the masses of the most abundant naturally
occuring isotopes of the various atoms that make up the molecule (with a correction
for the masses of the electron(s) lost or gained). For example, the mass of the molecular
ion of ethyl bromide C sub 2 /sub H sub 5 /sub sup 79 /sup Br will be 2 x 12 plus
5 x 1.0078246 plus 78.91839 minus the mass of the electron (m e). This is equal to
107.95751 u- me, u being the unified atomic mass unit based on the standard that the
mass of the isotope sup 12 /sup C 12 u exactly.;
Origin ID : M03988;
See also
An ion formed by the removal from (positive ions) or addition to (negative ions) a
molecule of one or more electrons without fragmentation of the molecular structure.
The mass of this ion corresponds to the sum of the masses of the most abundant naturally
occuring isotopes of the various atoms that make up the molecule (with a correction
for the masses of the electron(s) lost or gained). For example, the mass of the molecular
ion of ethyl bromide C sub 2 /sub H sub 5 /sub sup 79 /sup Br will be 2 x 12 plus
5 x 1.0078246 plus 78.91839 minus the mass of the electron (m e). This is equal to
107.95751 u- me, u being the unified atomic mass unit based on the standard that the
mass of the isotope sup 12 /sup C 12 u exactly.
