1
Introduction
How Should I Set Up the MS Detector for Various LC Flow Rates?
Thermo Electron Corporation
LTQ XL Getting Started
11
How Should I Set Up
the MS Detector for
Various LC Flow
Rates?
The ESI probe can generate ions from liquid flows
2
of 1
μ
L/min to
1.0 mL/min. This flow rate range allows you to use a wide range of
separation techniques: CE, CEC, capillary LC, microbore LC, and
analytical LC.
The APCI probe can generate ions from liquid flows
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of 200
μ
L/min to
2.0 mL/min. This flow range allows you to use microbore LC, analytical
LC, and semi-preparative LC.
As you change the rate of flow of solvents entering the MS detector, you
need to adjust several of the MS detector parameters, as follows:
For ESI, you need to adjust the capillary temperature and adjust the gas flow
rates for the Sheath, Auxiliary, and/or Sweep gas.
For APCI, you need to adjust the capillary temperature and vaporizer
temperature and adjust the gas flow rates for the Sheath, Auxiliary, and/or
Sweep gas.
In general, an increase in the rate of liquid flowing into the MS detector,
requires a higher temperature of the ion transfer capillary (and vaporizer)
and the higher gas flow rate.
provides guidelines for ESI operation for ion transfer capillary
temperatures and gas flow rates for various LC solvent flow rates.
Table 3
provides guidelines for APCI operation for the ion transfer capillary
temperature, vaporizer temperature, and gas flow rate for a range of LC
solvent flow rates.
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The ESI probe can generate ions from liquid flows of as low as 1
μ
L/min. However, flows below
5
μ
L/min require more care, especially with the position of the fused silica sample tube within the ESI
probe.
3
For the APCI probe, flows below 200
μ
L/min require more care to maintain a stable spray.
