Inficon Micro GC Fusion 2-Module User Manual

5 | Product Overview INFICON
38 / 319 074-594-P1H Micro GC Fusion Operating Man-
ual
5.7.1.4 Backflush Injector
The backflush assembly consists of:
• a backflush injector
• a pre-column
• an analytical column
The pre-column is a short section of column connected in series to the analytical
column. The pre-column prevents contaminants from entering the analytical column.
After the sample enters the analytical column, the flow is reversed (backflushed)
through the pre-column, flushing undesired components from the pre-column to vent.
Backflushing the pre-column prevents strongly retained compounds from entering the
analytical column and causing ghost peaks on subsequent runs.
The Backflush Injector has two method parameters:
Backflush Time
(in seconds) and
Inject (ms)
time (in milliseconds).
Valid
Backflush Time
set points range from 0 to 250 s.
Valid
Inject (ms)
time set points range from 0 to 250 ms.
The
Backflush Injector
can function in a semi-fixed mode. An
Inject (ms)
time of 0 ms
will result in a fixed injection volume. This is best used for component concentrations
above 0.1%, and will result in higher precision.
For component concentrations below 0.1%, the backflush injector can be operated as
a variable volume injector. An
Inject (ms)
time greater than 10 ms will allow larger
sample volumes to be injected, which in turn results in higher sensitivity on a µTCD.
Backflush times vary with column types, lengths, head pressure and temperature set
points. Backflush times should be optimized for each GC module.
5.7.2 Separation
Depending on the GC column used, separation is primarily based on the component
boiling point or polarity. The table below contains a list of common components that
can be separated on various GC column types.
GC Column Compounds Separated
Molsieve 5a hydrogen, oxygen, nitrogen, methane, carbon monoxide
PLOT U air, methane, carbon dioxide, ethylene, ethane, acetylene, propane,
hydrogen sulfide, carbonyl sulfide
PLOT Q air, methane, carbon dioxide, ethane, ethylene/acetylene, propane,
propylene, C4-C8 hydrocarbons, hydrogen sulfide
Alumina C4 and C5 hydrocarbons and olefins, 1,3-butadiene
PDMS C4-C12 hydrocarbons, hydrogen sulfide, volatile organic compounds

Inficon Micro GC Fusion 2-Module Specifications

General

Brand	Inficon
Model	Micro GC Fusion 2-Module
Category	Measuring Instruments
Language	English