Atmospheric pressure chemical ionization interface |
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| Acronym | APCI |
|---|---|
| Classification | Mass spectrometry |
| Analytes | Organic molecules Biomolecules |
| Other techniques | |
| Related | Chemical ionization Electrospray |
| Hyphenated | Liquid chromatography-mass spectrometry |
Atmospheric-pressure chemical ionization (APCI) is an ionization method used in mass spectrometry. It is a form of chemical ionization which takes place at atmospheric pressure.[1]
APCI allows for the high flow rates typical of standard bore HPLC to be used directly, often without diverting the larger fraction of volume to waste. Typically the mobile phase containing eluting analyte is heated to relatively high temperatures (above 400 degrees Celsius), sprayed with high flow rates of nitrogen and the entire aerosol cloud is subjected to a corona discharge that creates ions. Often APCI can be performed in a modified ESI source. The ionization occurs in the gas phase, unlike ESI, where the ionization occurs in the liquid phase. A potential advantage of APCI is that it is possible to use a nonpolar solvent as a mobile phase solution, instead of a polar solvent, because the solvent and molecules of interest are converted to a gaseous state before reaching the corona discharge pin. Typically, APCI is a less "soft" ionization technique than ESI, i.e. it generates more fragment ions relative to the parent ion.[2]
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