Page 222 - Tandem Techniques
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A Hewlett-Packard gas chromatograph was used, equipped with two matched silicone gum columns
and a single injection system. The matched columns gave a 50-50 split ratio of the injected sample. The
FTIR instrument was a Digilab FTS-45 spectrometer, equipped with an interface that captured the
eluted material onto a ZnSe plate held a low temperature ((Digilab Tracer). This plate acted as a
transport medium to transfer the sample to the FTIR spectrometer. The mass spectrometer was the
Hewlett-Packard 5970B mass selective detector. An example of chromatograms of the polychlorinated
biphenyls obtained from the combined instrumentation are shown in figure 525. It is seen that excellent
separations are displayed by both the ion current monitor and the integrated absorption spectra from the
FTIR spectrometer. It is also seen that most of the isomers (all those for which reference spectra were
available) were identifiable.
Figure 5.26
The IR Spectrum from 25 ng of 3,3',4,5-Tetrachlorobiphenyl
obtained from the GC -FTRI Tracer Unit (ref.27)
The sensitivity of the cryostat interface and the FTIR was extremely high, the spectra shown in figure
5.26 was obtained from only 25 ng of sample
