4-2 Optional APCI Mode of Operation
Atmospheric pressure chemical ionization
APCI, an option for the instrument, produces singly charged protonated or
deprotonated molecules for a broad range of nonvolatile analytes.
The APCI interface consists of the standard source fitted with a corona pin
and a heated IonSABRE APCI probe. Mobile phase from the ACQUITY UPLC
column enters the probe, where it is pneumatically converted to an aerosol,
rapidly heated, and vaporized or gasified at the probe tip.
APCI mode
Hot gas from the IonSABRE APCI probe passes between the sample cone and
the corona pin, which is typically operated with a discharge current of 5 µA.
Mobile phase molecules rapidly react with ions generated by the corona
discharge to produce stable reagent ions. Analyte molecules introduced into
the mobile phase react with the reagent ions at atmospheric pressure and
typically become protonated (in the positive ion mode) or deprotonated (in the
negative ion mode). The sample and reagent ions then pass through the
sample cone and into the mass spectrometer.
IonSABRE APCI probe
In the IonSABRE APCI probe, the nebulized gas plume expands in a directly
heated region with a larger internal diameter. The increased aerosol
expansion gives more efficient droplet evaporation than the standard ESI
probe. The nebulizer support gas controls the droplet residence times and
positively sweeps the sample from the probe, giving optimized probe
performance. The gas flow must be maintained at all times.
IonSABRE APCI probe
Sample cone
Corona pin
To Next Page
Loading...
Need help?
General
