Introduction 1
Troubleshooting and Maintenance Manual 11
In this manual, the term “CI MS” refers to the 7000 Series Triple Quad GC/MS
CI source system. It also applies, unless otherwise specified, to the flow
modules for these instruments.
The 7000 Series Triple Quad GC/MS CI source system upgrade kit adds to the
7000 Triple Quad MS:
• EI/CI GC/MS interface
• High sensitivity EI source
• CI ion source and interface tip seal
• Reagent gas flow control module
• HED with high sensitivity electronics
• 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.
The MS CI system has been optimized to achieve the relatively high source
pressure required for CI while still maintaining high vacuum in the collision
cell, quadrupoles, 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
insulating seal fits onto the tip of the interface.
Switching back and forth between CI and EI sources takes less than an hour,
although a 1- to 2-hour wait is required to purge the reagent gas lines and bake
out water and other contaminants. Switching from PCI to NCI requires about 2
hours for the ion source to cool.
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