Waters GCT Premier - Ion Source; Electron Ionization;Chemical Ionization (EI;CI) Outer Source Assembly; Field Ionization;Field Desorption Ionization (FI;FD) Outer Source Assembly

Ion source 1-3
at a given moment, regardless of how rapidly the sample composition is
changing.
See also: Appendix G Theory and Principles of Operation for details of the
electron ionization (EI), chemical ionization (CI) field ionization (FI), and field
desorption ionization (FD) techniques, and the ion optics in the instrument.
Ion source
The outer ion source consists of two assemblies:
• EI/CI/DCI outer source assembly
• FI/FD outer source assembly
The ion source is at ground potential, allowing simple, direct-coupling to the
GC inlet. The instrument can operate in positive and negative EI and CI
modes and positive FI and FD modes.
Electron ionization/chemical ionization (EI/CI) outer source
assembly
You access the outer source assembly from the top of the instrument,
removing the outer source lid assembly cover. The outer source assembly
comprises, a source heater and focusing and transfer optics. Heaters in the
outer source raise the source temperature to ensure sample vaporization and
avoid condensation of analytes onto the inner source and lenses.
See also: Changing the EI/CI outer source assembly on page 2-6.
Field ionization/field desorption ionization (FI/FD) outer source
assembly
Field ionization (FI) is a process in which spectra with little or no
fragmentation are obtained. It is used to detect and exactly measure
molecular ions, which can be weak or absent in EI mode.
The FI/FD outer source assembly is used only with the FI/FD inner source. It
comprises the extraction rods, emitter contacts and focussing and transfer
optics. It is accessed from the top of the instrument.
See also: Changing the FI/FD outer source assembly on page 9-3.