Practical Techniques for LC/MS Analysis
Terms and Definitions
API -Atmospheric Pressure Ionization
Atmospheric Pressure Ionization: Allows creation of ions at atmospheric pressure. Uses nebulizergas at 1 atmosphere to assist in drying liquid aerosol. Usually refers to the collection of techniques used to ionize solutes including APCI and ESI.
Source (called interface or probe by chromatographers)
ESI -Electrospray Ionization source
ESI: ElectrosprayIonization. The most common technique for ionizing molecules. Uses the ions formed in solution, evaporates the mobile phase using nebulizergas pressure, leave ions behind. Can produce singly or multiply charged ions depending on molecular structure.
APCI -Atmospheric Pressure Chemical Ionization source
APCI: Atmospheric Pressure Chemical Ionization. One of the other common ionization techniques used to interface HPLC to MS. Typically uses heat and gas pressure to dry droplets, and uses a electrical discharge to ionize mobile phase and gas that is used to transfer a chargeto the solute molecule. Only creates singly charged ions.
CID: Use of voltage and gas pressure in the first vacuum region to break ions into smaller fragments. Also called In-source fragmentation.
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