Thermo Finnigan LCQ Deca XP Plus, Hardware Manual

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Functional Description
API Source _________________________________________________________________
1-4
____________________ LCQ Deca XP Plus Hardware Manual ________________
The ESI probe accommodates liquid flows of 1 mL/min to 1 mL/min and
produces charged aerosol droplets that contain sample ions. The axis of the
ESI probe is orthogonal to the axis of the ion transfer capillary. See
Figure 1-3. The geometric arrangement of the ESI probe and the API stack
helps keep the ion transfer capillary clean.
The ESI probe includes the ESI sample tube, needle, nozzle, and manifold.
Sample and solvent enter the ESI probe through the sample tube. The sample
tube is a short section of 0.1 mm ID fused-silica tubing that extends from a
fitting secured to the grounded fitting holder, through the sample inlet and
into the ESI needle, to within 1 mm from the end of the ESI needle. The ESI
needle, to which a large negative or positive voltage is applied (typically
±
4.5
to
±
5 kV), sprays the sample solution into a fine mist of charged droplets. The
ESI nozzle directs the flow of sheath gas and auxiliary gas (if used) at the
droplets. The ESI manifold houses the ESI nozzle and needle and includes the
sheath gas, and auxiliary gas plumbing. The sheath gas plumbing delivers
dry nitrogen gas to nozzle. The auxiliary gas plumbing also delivers dry
nitrogen to the nozzle.
The sheath gas is the inner coaxial nitrogen gas that sprays (nebulizes) the
sample solution into a fine mist as it exits the sample tube. Typical sheath gas
flow rates for ESI are 60 units for sample flow rates of 3
µ
L/min and 80 units
for sample flow rates of 1 mL/min. (Typical sheath gas flow rates for APCI
are 60 units for sample flow rates of 100
µ
L/min, 80 units for sample flow
rates of 1 mL/min, and 85 units for sample flow rates of 2 mL/min.) When
you tune LCQ Deca XP Plus, you should adjust the sheath gas flow rate until
the ion signal is stable.
The auxiliary gas (if used
1
) is outer coaxial nitrogen gas that assists the
sheath gas in the nebulization and evaporation of sample solutions. Auxiliary
gas helps lower the humidity in the ion source. Typical auxiliary gas flow
rates for ESI and APCI are 10 to 20 units.
The sweep gas (if used
1
) is nitrogen gas that helps to improve the ruggedness
of your API source. Sweep gas is also useful for reducing solvent adducts and
chemical noise when using Full-scan MS or Data Dependent experiment
types.
Refer to Table 1-1 for specific guidelines for LC/ESI/MS operation.
1
Auxiliary gas and sweep gas cannot be used simultaneously. Refer to LCQ Deca XP Plus
Getting Started for help on determining whether auxiliary gas or sweep gas will best fit your
needs.