5.1.2 Ion Chromatograms as a Key Feature for in Depth
Examination
A more special feature in GC/MS analyses allow a more detailed investigation of the
data. Mass spectra are composed on the intensities of individual ions. The chromatogram obtained by GC/MS analyses consists of the total ion intensities (sum of
all ions per mass spectrum) in relation to the retention time. The chromatogram
consists of individual points, each of them representing one mass spectrum measured
in a short time period (e.g. 0.5 s). The chromatogram is called total ion chromatogram (see Fig. 5.13) and at each point of the chromatogram the corresponding mass
spectrum can be obtained. A variation of constructing a chromatogram is called ion
chromatogram, considering the intensities of only one ion within all the measured
mass spectra. This is also reflected in Fig. 5.13.
20
40
60
80
100
120
140
160
180
200
220
240
260
m/z
115
157
203
TIC
m/z 203
retention time
30
50
70
90
110
130
150
170
190
210
230
250
270 280
m/z
m/z
Fig. 5.13 Principals of ion chromatograms
5.1 Identification
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