To Set Up Methane Reagent Gas Flow - Agilent Technologies 5977B Series Operating Manual

5 Operating in CI Mode

To Set Up Methane Reagent Gas Flow

The reagent gas flow must be adjusted for maximum stability before tuning the
CI system. Do the initial setup with methane in PCI mode. No flow adjustment
procedure is available for NCI, as no negative reagent ions are formed.
Adjusting the methane reagent gas flow is a three-step process: setting the
flow control, pretuning on the reagent gas ions, and adjusting the flow for
stable reagent ion ratios, for methane, m/z 28/27.
Your data system will prompt you through the flow adjustment procedure.
Procedure
1 Using an EI source, perform the standard autotune, save the report, and note
2 Vent the system. (See
3 Install the CI source. (See
4 Pump out the system. (See
5 Wait until the pressure is near the previously recorded pressure for the EI
6 Select Bake out MSD from the Manual Tune view in the Execute menu to display
After the system has been switched from EI to CI mode, or vented for any other reason,
C A U T I O N
the MSD must be baked out for at least 2 hours before tuning.
Continuing with CI autotune if the MSD has an air leak or large amounts of water will
result in severe ion source contamination. If this happens, you need to vent the MSD
and clean the ion source.
7 Select Methane Pretune from the Setup menu and follow the system prompts.
130
the reported pressure. (See
page 124.)
autotune. (See "To Monitor CI Mode High Vacuum Pressure"
the Specify Bake Out parameters dialog. Set a minimum time of 2 hours, adjust
the other parameters, and click OK to begin the bake out.
See the Agilent MassHunter GC/MS Acquisition software online help for
additional information.
The methane pretune tunes the instrument for optimum monitoring of the
ratio of methane reagent ions m/z 28/27.
"To Tune the MSD in EI Mode"
"Venting the MSD" on page 91.)
"To Install the CI Source"
"To Pumpdown the MSD in CI Mode"
on page 104.)
on page 225.)
on page 141.)
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