Waters GCT Premier - Using the Calibration Wizard

5-4 Calibration
Lock mass intensity
When using the lock mass in experiments the lock mass compound is
continually introduced to the source from the reference reservoir throughout
the experiment. Before starting an acquisition using lock mass, make sure
that there is a constant signal of lock mass compound at the mass specified in
the TDC settings window and that the intensity is appropriate. The lock mass
peak should be over 1500 counts in centroid, in each spectrum, for good
statistical mass measurements. However, it must not be so strong as to be
saturated. Saturated peaks are indicated by a question mark above the peak
in a single spectrum view. If saturation is seen on the lock mass peak, then
the peak’s intensity must be reduced. Open the reference reservoir pump-out
valve until the intensity falls to a suitable value.
The Instrument Setup Wizard initially sets up the lock mass intensity.
See also: Obtaining an ion beam on page 3-3.
Using the Calibration wizard
When you run the calibration wizard, sample is injected into the reference
reservoir and data are acquired and compared to data in a reference file
containing the correct masses for some of the ions in the reference compound.
The instrument then calculates a calibration curve, and a graph with the
mean residual value (RMS) displayed.
See also: Figure titled “Calibration Graph window:” on page 5-10.
The mean residual value indicates the success of the calibration. For example,
a mean residual value of less than 1 mDa indicates that the calibration was
good. When the acquisition is saved, the calibration is displayed on the Tune
window and the file created is applied to all subsequent acquisitions.
Important: If you click Cancel while running the wizard, the wizard closes.
Existing calibrations are no longer valid and you must run them again.
To run the calibration wizard:
1. Use a septum-piercing syringe to introduce the reference sample into the
reference reservoir.
2. Adjust the intensity of the reference sample using the reference
reservoir pump valve to obtain approximately 1200 counts per second.
3. In the MassLynx Tune window, click Wizard > Calibration Wizard.