Thermo Scientific TSQ Altis, Руководство по оборудованию

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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 ).
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
mass-to-charge ratio ( m/z) in
the current spectrum.
6. Observe the RSD graph, and review the signal stability rating and %RSD value.
Table 12 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