5Methods
Operation Manual 107
Column compensation
In temperature programmed analysis, bleed from the column increases as the oven
temperature rises. This causes a rising baseline which makes peak detection and integration
more difficult. Column compensation corrects for this baseline rise.
A column compensation run is made with no sample injected. The GC collects an array of data
points from all 4 detectors, whether installed, off, or working. If a detector is not installed or is
turned off, that part of the array is filled with zeros.
Each array defines a set of curves, one for each detector, that can be subtracted from the real
run to produce a flat baseline. The next figure illustrates the concept.
Relative noise level
Slower data ratesFaster data rates
Excess noise (due to flow,
oven temperature, detector
block temperatures, etc.)
Chromatogram with
rising baseline
Chromatogram with
column compensation
Blank column
compensation
profile
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