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Multimode Source for 6100 Series Single Quad LC/MS Set-Up Guide 37
Methods 3
To create a method for positive/negative mixed mode operation
To create a method for positive/negative mixed mode operation
1 Open the MSD Spray Chamber dialog box by clicking the Instrument > Set
Up MSD Signals in the Method and Run Control view.
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
Spray chamber in the Method and Run Control view.
7 Modify the settings so that Signal 1 has Positive polarity and Signal 2 has
Negative polarity as shown in Figure 21.
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.