Waters Xevo G2 QTof, Руководство оператора, обзор и техническое обслуживание, Страница: 26 / 248

1-8 Waters Xevo G2 QTof Overview
The standard ESI probe capillary accommodates flow rates of up to 2 mL/min
making it suitable for LC applications in the range 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 200 µL/min.
Atmospheric pressure chemical ionization (APCI)
Atmospheric pressure chemical ionization (APCI) produces singly-charged
protonated or deprotonated molecules for a broad range of nonvolatile
analytes.
To operate the LockSpray source in APCI mode, you fit the source enclosure
with a corona pin and an APCI 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.
APCI mode:
Hot gas from the APCI probe passes between the sample cone and the corona
pin. 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.
APCI probe
Sample cone
Corona pin