2000 MS Hardware Maintenance
58
Chemical Ionization Options
The values of each parameter for acetonitrile CI are identified in the table
Default
Parameters for Liquid CI Reagents
and already entered into the fields on the
right side of the table. (If we were setting up for any of the standard gaseous or
liquid reagents, their parameters can be entered automatically by clicking on the
appropriate Reagent Gas selection. Parameters for other CI reagents may be
entered by clicking on the User-Defined selection and entering user-selected
parameters.)
Once the CI parameters are chosen, click on the Segment Setpoints tab dialog
and choose values for other parameters. The default for ARC Target count is
5000 count for all reagents. Values up to 20,000 are commonly used. You may
also want to select an Emission Current specific to the Tune File. Generally an
emission current of 10-20
µ
A is used in CI acquisitions.
When you have finished these steps save the Method for Channel A with the
menu command
File…Save As
ChannelA.mth.
Modify this method for the CI reagents in Channels B and C and save the new
methods with the menu command
File…Save As
ChannelB.mth or
ChannelC.mth. You may then activate the files from System Control with the
menu command
File…Activate
.
Adjusting Reagent Flow for Each CI Reagent
1. Connect a liquid reagent reservoir containing the chosen liquid or connect a
selected gas supply to Channel A, B, or C in the MCI Module inlet block. Use
the procedures in
Adding Liquid CI Reagents to the MCI Module
or
Adding Gaseous Reagents to the MCI Module
.
2. Open the CI needle valve for the chosen Channel 6-7 turns counterclockwise.
3. Open the CI solenoids for the chosen Channel either from the GC keyboard or by
activating a method for that reagent (ChannelA.mth, ChannelB.mth, or
ChannelC.mth with the System Control menu command
File…Activate Method
.
In this case, the method ChannelA.mth is activated.
4. Enter the Manual Control dialog of Saturn System Control. Click on the CI button
in the Saturn icon on the upper left of the screen and allow a few seconds for the
vapor flow from the reservoir to equilibrate. The set of tab dialogs in the center of
