Atmospheric Pressure Chemical Ionization (Apci); Combined Electrospray/Atmospheric Pressure Chemical Ionization (Esci) - Waters Xevo G2-XS QTof Overview And Maintenance Manual

The standard ESI probe capillary accommodates flow rates of up to 2 mL/min, making it suitable
for LC applications in the range of 100 µL/min to 2 mL/min. To reduce peak broadening for lower
flow rate LC applications, such as 1-mm UPLC columns, use the optional, small-bore capillary,
which can accommodate a maximum flow rate of 100 µL/min.

1.2.2 Atmospheric pressure chemical ionization (APCI)

APCI produces singly charged protonated or deprotonated molecules for a broad range of
nonvolatile analytes.
The APCI interface consists of the ESI/APCI enclosure fitted with a corona pin and an IonSABRE
II probe. Mobile phase from the LC column enters the probe, where it is pneumatically converted
to an aerosol, rapidly heated, and vaporized or gasified at the probe tip.
Figure 1–4: APCI mode
Corona pin
Sample cone
IonSABRE II probe
Hot gas from the IonSABRE II 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.
1.2.3 Combined electrospray/atmospheric pressure chemical
ionization (ESCi)
In combined electrospray and atmospheric pressure chemical ionization (ESCi) mode, the
standard ESI probe is used in conjunction with a corona pin. The design allows alternating
acquisition of ESI and APCI ionization data, facilitating high-throughput processing and wider
compound coverage.
March 31, 2021, 715004496 Ver. 04 (previously released as Rev. D)
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