fragment ion

fragment ion

A term defined in the context of mass spectrometry as the charged product of an ion dissociation. A fragment ion may be stable or dissociate further to form other charged fragment ions and neutral species of successively lower mass. Molecular ions formed in the initial ionisation dissociate to fragment ions because of excess internal energy remaining after ionisation.
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If the interfering compound is present in much higher concentrations than the target analyte, substantial inaccuracy may result even if only a less abundant fragment ion of the interfering compound shares the m/z ratio of the target analyte.
These peptides can be quantified by use of selected reaction monitoring, which specifically selects the mass-to-charge ratio (m/z) of an enzyme-generated peptide and then detects a specific fragment ion of the peptide generated within the mass spectrometer.
0 Da of the mass of a monitored fragment ion from the desired analyte), then an interference results.
This is likely to be true in the MSZ event in the ion-trap, where only 1 major fragmentation pathway is followed (see the online Data Supplement), but when MS/MS is performed on both the tandem quadrupole and Q-TOF instruments, where fragmentation is dispersed over a wide range of fragment ions, it is to be expected that the 2 isomers will give different relative abundance for each fragment ion.
MS/MS usually offers high specificity, even in complex sample matrices, through selection of a specific precursor ion in the first mass analyzer and selection of a specific fragment ion formed during passage of the precursor ion through a collision cell.
Another peak observed at m/z 203 (C11H7NO3) was due to the loss of isopropyl (C3H7) group of the side chain of fragmented ion C14H16NO3 (m/z 246), which on further loss of CH2O yielded m/z 173 fragment ion corresponding to C10H5NO2.
A fragment ion at m/z 306 refers to the deprotonated glutathione (GSH) moiety and CNLs of 120 and 146, indicating the presence of a rhamnoside group.
Specificity: Selection of the precursor ion with the first quadrupole and the product fragment ion with the second quadrupole by the tandem mass spectrometer can exhibit highly specific detection for a given molecule.