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[4] [5] Mass spectrometry ionization techniques requiring the sample to be in the gas phase have similar concerns. Electron ionization (EI) in mass spectrometry requires samples that are small molecules, volatile, and thermally stable, similar to that of gas chromatography. This ensures that as long as GC is performed on the sample before ...
Chemical ionization (CI) is a soft ionization technique used in mass spectrometry. [ 1 ] [ 2 ] This was first introduced by Burnaby Munson and Frank H. Field in 1966. [ 3 ] This technique is a branch of gaseous ion-molecule chemistry. [ 2 ]
Atmospheric pressure chemical ionization chamber cross section. Atmospheric pressure chemical ionization (APCI) is an ionization method used in mass spectrometry which utilizes gas-phase ion-molecule reactions at atmospheric pressure (10 5 Pa), [1] [2] commonly coupled with high-performance liquid chromatography (HPLC). [3]
A certain amount of energy, which may be large enough, is required to remove an electron from an atom or a molecule in its ground state. [12] [13] In chemi-ionization processes, the energy consumed by the ionization must be stored in atoms or molecules in a form of potencial energy or can be obtained from an accompanying exothermic chemical change (for example, from a formation of a new ...
Atmospheric pressure photoionization (APPI) is a soft ionization method used in mass spectrometry (MS) usually coupled to liquid chromatography (LC). Molecules are ionized using a vacuum ultraviolet (VUV) light source operating at atmospheric pressure (105 Pa), either by direct absorption followed by electron ejection or through ionization of a ...
The low fragmentation ionization allows for identification based on the molecular mass as protonated [M+H]+ species. This can be particularly useful in combination with high-resolution mass spectrometers such as time-of-flight mass spectrometers (TOF-MS) or Orbitrap-MS for non-target analysis, where the entire substance spectrum of a sample is ...
In mass spectrometry, direct analysis in real time (DART) is an ion source that produces electronically or vibronically excited-state species from gases such as helium, argon, or nitrogen that ionize atmospheric molecules or dopant molecules. The ions generated from atmospheric or dopant molecules undergo ion-molecule reactions with the sample ...
Techniques for ionization have been key to determining what types of samples can be analyzed by mass spectrometry. Electron ionization and chemical ionization are used for gases and vapors. In chemical ionization sources, the analyte is ionized by chemical ion-molecule reactions during collisions in the source.