Galvanic Applied Sciences AccuChrome MA2963, Operation Manual

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Revision 4 109 12/15/2018
11.5 The Chromatograph Output: The Chromatogram
The signal output by the TCD is used to generate a chromatogram, which is a graph of
detector response against time. The presence of a component will generate a spike in the
TCD’s response, which appears as a ‘peak’ on the chromatogram. The components are
identified by the microprocessor according to the length of time it takes them to elute from the
column. The concentration of each component is calculated using a response factor
determined during calibration with a certified standard. Figure 11-4 shows the different
characteristics and definitions of a typical chromatogram, assuming two components called
‘A’ and ‘B’.
Figure 11-4: Chromatogram Description
t
M
-
dead time:
time for non-retained species to move through the column.
V
M -
-
dead volume:
volume of mobile phase in the column.
t
R
- retention time: the time it takes a component band to completely travel through the
column. Each component will have a characteristic retention time.
V
R
-
retention volume
- the volume of gas that passes through the column between the point
of injection and the peak maximum of the component.
A
- peak area - response is proportional to the concentration of the component.
h - peak height - the distance between the peak maximum and the baseline geometrically
produced beneath the peak.
Baseline
Peak