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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 ...
A mass chromatogram is a representation of mass spectrometry data as a chromatogram, where the x-axis represents time and the y-axis represents signal intensity. [1] The source data contains mass information; however, it is not graphically represented in a mass chromatogram in favor of visualizing signal intensity versus time.
The use of the term mass spectroscopy is now discouraged due to the possibility of confusion with light spectroscopy. [1] [8] Mass spectrometry is often abbreviated as mass-spec or simply as MS. [1] Modern techniques of mass spectrometry were devised by Arthur Jeffrey Dempster and F.W. Aston in 1918 and 1919 respectively.
The mass spectrum of methylbromide has two prominent peaks of equal intensity at m/z 94 (M) and 96 (M+2) and then two more at 79 and 81 belonging to the bromine fragment. Even when compounds only contain elements with less intense isotope peaks ( carbon or oxygen ), the distribution of these peaks can be used to assign the spectrum to the ...
Most metal chlorides with the metal in low oxidation states (+1 to +3) are ionic. Nonmetals tend to form covalent molecular chlorides, as do metals in high oxidation states from +3 and above. Both ionic and covalent chlorides are known for metals in oxidation state +3 (e.g. scandium chloride is mostly ionic, but aluminium chloride is not).
In the selected ion flow tube mass spectrometer, SIFT-MS, ions are generated in a microwave plasma ion source, usually from a mixture of laboratory air and water vapor. . From the formed plasma, a single ionic species is selected using a quadrupole mass filter to act as "precursor ions" (also frequently referred to as primary or reagent ions in SIFT-MS and other processes involving chemical ...
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.
Finally, the ionization products MH + (H 2 O) m transfer out from the atmospheric-pressure ion source. Declustering (removal of water molecules from the protonated analyte molecule) of MH + (H 2 O) m takes place at the high vacuum of the mass analyzer. [2] The analyte molecule ions detected by MS are [M+H] +. The chemical reactions of ...