Search results
Results from the WOW.Com Content Network
A mass spectrum is a histogram plot of intensity vs. mass-to-charge ratio (m/z) in a chemical sample, [1] usually acquired using an instrument called a mass spectrometer. Not all mass spectra of a given substance are the same; for example, some mass spectrometers break the analyte molecules into fragments ; others observe the intact molecular ...
Mass spectral interpretation is the method employed to identify the chemical formula, characteristic fragment patterns and possible fragment ions from the mass spectra. [ 1 ] [ 2 ] Mass spectra is a plot of relative abundance against mass-to-charge ratio.
Data analysis is generally challenging for DIA methods as the resulting fragment ion spectra are highly multiplexed. In DIA spectra therefore the direct relation between a precursor ion and its fragment ions is lost since the fragment ions in DIA spectra may potentially result from multiple precursor ions (any precursor ion present in the m/z range from which the DIA spectrum was derived).
In mass spectrometry, fragmentation is the dissociation of energetically unstable molecular ions formed from passing the molecules mass spectrum.These reactions are well documented over the decades and fragmentation patterns are useful to determine the molar weight and structural information of unknown molecules.
When presenting data, it is common to use the (officially) dimensionless m/z, where z is the number of elementary charges (e) on the ion (z=Q/e). This quantity, although it is informally called the mass-to-charge ratio, more accurately speaking represents the ratio of the mass number and the charge number, z .
Table 1. Mass of amino acid fragment ions [4] [13] For interpretation, [14] first, look for single amino acid immonium ions (H 2 N + =CHR 2). Corresponding immonium ions for amino acids are listed in Table 1. Ignore a few peaks at the high-mass end of the spectrum. They are ions that undergo neutral molecules losses (H 2 O, NH 3, CO 2, HCOOH ...
ECD produces significantly different types of fragment ions (although primarily c- and z-type, b-ions have been identified in ECD [9]) than other MS/MS fragmentation methods such as electron-detachment dissociation (EDD) (primarily a and x types), [10] [11] [12] collision-induced dissociation (CID) (primarily b [13] and y type) and infrared ...
A table or chart of nuclides is a two-dimensional graph of isotopes of the elements, in which one axis represents the number of neutrons (symbol N) and the other represents the number of protons (atomic number, symbol Z) in the atomic nucleus. Each point plotted on the graph thus represents a nuclide of a known or hypothetical chemical element.