15
Calibrating the MS
Evaluating the Spray Stability
Thermo Scientific
TSQ Altis, Quantis, and Fortis Hardware Manual
59
The MS begins to scan and applies high voltage to the spray insert. A real-time mass
spectrum appears in the Tune window.
4. Click
Syringe Off
to turn on the syringe pump.
A real-time plot of the EMRS mass spectrum appears.
5. Plot the ion chromatogram and
relative standard deviation (RSD)
graphs as follows:
a. Click the
Plot Chromatogram
icon,
, to open the Plot Chromatogram dialog
box (
).
Figure 27.
Plot Chromatogram dialog box
b. To monitor the RSD of the target ion current, select the
Spray Stability
check box.
c.
Select the
User Defined m/z
option, add a table row by clicking the + icon (upper
right of the table), and type
622
(positive mode) or
602
(negative mode) in the Mass
column.
d. To plot the specified chromatogram, click
OK
.
The Plot Chromatogram tool generates a real-time graph (plot) where you can
observe the signal stability and the effects of changes to various parameters. The tool
also generates a real-time graph of the RSD for a 10 Da-selected ion monitoring
(SIM) scan that is centered around the most abundant
the current spectrum.
6. Observe the RSD graph, and review the signal stability rating and %RSD value.
lists the criteria for a stable spray in either positive or negative ion polarity mode.
z
7. If the signal stability rating is poor or the %RSD value is above the threshold, optimize
the API source parameters.
a. Adjust the sheath gas plus or minus 1 unit.
Table 12.
Recommended %RSD values and ratings for the calibration solutions
Ion polarity mode
Acceptable signal
stability rating
Maximum %RSD
(threshold)
Positive
Excellent or Good
15
Negative
Excellent or Good
15
