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To create a method for positive/negative mixed mode operation
1 Open the MSD Spray Chamber dialog box by clicking the Instrument > Set
2 Select MM-ES_APCI from the Method Spray Chamber drop-down list.
3 Check that Installed Spray Chamber is also set to MM-ES+APCI.
4 Make any other changes that are necessary for your method.
5 Click the OK button.
6 Open the Set up MSD Signals dialog box by clicking the Instrument > MSD
7 Modify the settings so that Signal 1 has Positive polarity and Signal 2 has
8 Make any other changes that are necessary for your method.
9 Click the OK button.
Fast positive/negative polarity switching is a very useful technique but it
requires time for the ion chemistry to be established and the optics path to
refill with ions. The gas density plays a role in the speed of refilling the ion
path. The gas density is affected by source temperature. For a method running
positive/negative switching, use a lower vaporizer temperature (150 to 200°C)
and a lower Vcap (approximately 1000 V). These will greatly affect the quality
of the results in positive/negative switching experiments.
Multimode Source for 6100 Series Single Quad LC/MS Set-Up Guide
To create a method for positive/negative mixed mode operation
Up MSD Signals in the Method and Run Control view.
Spray chamber in the Method and Run Control view.
Negative polarity as shown in
Figure
21.
Methods
3
37
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