molecular ion


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molecular ion

An ion formed by removing (positive ion), or adding (negative ion), one or more electrons from a molecule M to form M• or M••.  The mass of the molecular ion corresponds to the molecule’s nominal or monoisotopic mass; the mass of the electron added or lost is usually inconsequential. The molecular ion mass is the sum of the relative masses of the most abundant naturally occurring isotopes of the various atoms comprising the molecule.
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The early eluting peaks at ~3.5 min gave a protonated molecular ion at m/z 148, which corresponded to glutamic acid and cochromatographed with pure L-glutamic acid.
In this process, the ion collides with neutral gas molecules and then fragments to yield smaller ions whose masses depend on the structure of the original molecular ion. Thus, structural information as well as the molecular weight of an unknown compound may be obtained.
The only difference was observed in mass spectral data of 2, as HR-EI-MS displayed molecular ion at m/z 517.4462 corresponding to the molecular formula C 33 H 59 NO 3 .
The molecular ions [[M + H].sup.+] and [[M + [NH.sub.4]].sup.+] were observed for all dicarboxylic acids that were evaluated, including MMA, SA, malonic, 2-hydroxyglutaric, adipic, ethylmalonic (EMA), dimethylmalonic (DiMMA), suberic, sebacic, and dodecanedioic acids.
Thus it showed the presence of the molecular ion peak at 339 and a number of fragments agree with the proposed structure (Scheme-1).
The HR-EI-MS displayed molecular ion at m/z 328.0938 corresponding to the molecular formula C18H16O6 with one oxygen atomless than that of 1.
With a single injection into the combined system, MS data identifies the tricresyl phosphate peaks from their distinctive molecular ion at m/z 368.
Because the molecular ions of N-alkylated carbamic acids are stable during GC-MS analysis, the M/M+1 and F/F+1 peak ratios can be easily measured by this technique.
The exposed surfaces contain significantly higher quantities of contaminants such as Li, Na, Mg, Si, and K, as well as significantly higher levels of low-mass, oxygen-containing molecular ion species such as [CHO.sup.+], [C.sub.2][H.sub.3][O.sup.+], and [C.sub.3][H.sub.3][O.sup.+].
This spectrum was acquired by transmitting the protonated molecular ion via [Q.sub.1] and scanning the second resolving quadrupole ([Q.sub.3]) for products resulting from fragmentation in the collision cell.
The M8 metabolite is not shown because its molecular ion was not monitored.
1 shows the parent ion spectrum of the molecular ion (precursor ion) for pure octanoylcarnitine and [[sup.2][H.sub.3]]octanoylcarnitine.

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