INFICON 3000 Micro GC Gas Analyzer Operating Manual - Manual (Page 243)

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3000 Micro GC Operating Manual
9.2.1.3.3 Extra Peaks
Extra (ghost) peaks are peaks that appear during a blank run, and peaks that
appear during a sample run. Ghost peaks appear even when no sample is injected
(and are also found among the genuine peaks during a sample run).
Ghost peaks appear during a blank run
 The column has been heated and idle for an extended period of time
 Carrier gas and plumbing impurities such as oils, greases and other materials.
 Reaction of the stationary phase with trace levels of oxygen, water and other
materials in the carrier gas.
 Contaminated inlet. Residues in the inlet are volatilized or pyrolyzed and swept
onto the head of the column. If reducing the Inlet Temperature eliminates or
reduces ghost peaks, the inlet requires cleaning.
 Contaminated sample conditioner. If the sample conditioner contains a filter,
replace the filter.
Additional peaks appear when pure sample is injected
 Sample is not pure, causing ghost peaks. Run a blank (carrier gas only). If the
peaks persist, they are not sample-related.
 Thermal degradation of one or more components by an overheated inlet.
Reduce the Inlet Temperature.
 Sample carryover, causing ghjost peaks. Run time is not adequate for all the
sample compounds to elute. Compounds carried over appear as broad peaks
during the second run. This can be eliminated by increasing Column
Temperature or increasing sample Run Time. If applicable, adjust Backflush
Time until all sample components appear during a run.