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Introduction
What is Tuning and Calibration of the MS Detector All About?
Thermo Electron Corporation
LTQ XL Getting Started
13
What is Tuning and
Calibration of the MS
Detector All About?
To optimize the performance of data acquisition on the LTQ XL MS
detector, tune and calibrate in four steps:
• In ESI mode, you infuse a calibration solution into the MS detector at a
steady rate of 5
μ
L/min for several minutes. In Tune Plus, you observe
the signal at
m/z
195, the mass-to-charge ratio of caffeine in the
calibration solution. Then, while observing the signal at
m/z
195, you
adjust probe positions and gas flows to achieve the greatest signal
strength while still maintaining a stable spray of ions into the MS
detector.
• Once you have established a stable spray of ions into the MS detector,
tune the MS detector. In this step, you use the automatic tuning
procedure in Tune Plus to ensure that the transmission of ions into the
MS detector is optimum. You observe the Tune Plus window as the
Xcalibur data system tunes your LTQ XL MS detector automatically.
• After your tune method is optimized, calibrate the MS detector. In this
step, you want to ensure that the calibration parameters complete
automatic calibration successfully. The Calibrate dialog box in Tune
Plus provides a readback of the status of the calibration parameters, both
during the automatic calibration and when calibration is complete.
• Lastly, if you want to maximize the detection of one or more particular
ions, you can optimize the tune of the MS detector with your analyte of
interest in the ionization mode that you are going to use to analyze your
samples. You choose a mass-to-charge ratio of your analyte of interest.
Alternatively, you can choose an ion in the calibration solution that is
closest to the mass-to-charge ratio for your ion of interest. (It is
sometimes possible to acquire qualitative data without optimizing the
parameters, but detection sensitivity might be compromised.)
Calibration parameters are instrument parameters whose values do not vary
with the type of experiment. It is recommended that you calibrate the MS
detector at least once every three months and that you check the calibration
about once a week.
Automatic and semi-automatic calibration (including checking the
calibration) require that you introduce calibration solution into the MS
detector at a steady flow rate while the procedure is running. You introduce
the solution directly from the syringe pump into the MS detector in the
ESI/MS mode.