1Introduction
MSD Hardware Description
18 5977C GC/MSD Operating Manual
The 5977C Series CI system field upgrade adds the following to the 5977C Series
MSD:
• EI/CI GC/MSD interface
• JetClean option that shares the same MFC system EI/CI GC/MSD interface
• CI source with the new common interface tip seal that can also be used with
an EI XTR source or HES
• Reagent gas MFC
• Bipolar HED power supply for PCI and NCI operation
A methane/isobutane gas purifier is provided and is required. It removes oxygen,
water, hydrocarbons, and sulfur compounds.
A high vacuum gauge controller (G3397B) is integrated in the system. Its use is
required for CI, and it is recommended for EI also.
The CI system has been optimized to achieve the relatively high CI source
pressure required for CI while still maintaining high vacuum in the quadrupole
and detector. Special seals along the flow path of the reagent gas and very small
openings in the ion source keep the source gases in the ionization volume long
enough for the appropriate reactions to occur.
The CI interface has special plumbing for reagent gas. A spring-loaded tip seal
fits onto the ion source end of the GC/MSD interface.
Switching back and forth between CI and EI sources takes less than an hour,
however, a 1- to 2-hour wait is required to purge the reagent gas lines and bake
out water and other contaminants.
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