3.2.2 ESCi mode
To operate in ESCi mode, you must fit an ESI probe adaptor and corona pin to the source
enclosure.
The system, with the ESI probe adaptor installed and corona discharge pin fitted, can alternate
between ESI and APCI ionization modes, facilitating data acquisition in ESI and APCI modes in
parallel.
3.2.3 APCI mode
APCI mode, an option for the mass spectrometer, produces singly charged protonated or
deprotonated molecules for a broad range of nonvolatile analytes.
The APCI interface consists of the ESI/APCI/ESCi enclosure fitted with a corona pin and an APCI
probe adaptor. 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 3–1: APCI mode:
APCI probe
Corona pin
Sample cone
Hot gas from the 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.
3.2.4 Configuring for ESI/ESCi/APCI modes
To operate in ESI, ESCi or APCI mode, you must fit the correct probe adaptor and install a probe
assembly.
June 9, 2016, 715004990 Rev. A
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