Page 321 - Tandem Techniques
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The chromatograms demonstrates the effect of the deposition interface on the chromatographic
resolution. It is seen that the integrity of the separation is not significantly impaired by the spraying
technique. It was found there was an optimum distance for the jet to project beyond the sheath flow jet,
and there was an optimum distance between the end of the deposition jet and the transport medium
surface. These optimum distances were found to be approximately the same, that is about 0.5 mm and
0.5 mm respectively. It was also found that a zinc selenide window gave better spectra than a
aluminized reflective surface when used as transport media. A three-dimensional reversed phase LC/IR
plot for the separation of some polynuclear aromatic hydrocarbons is shown in Figure 8.11
Figure 8.11
A Three-dimensional Reversed Phase LC/IR Plot of the
Separation of Some Polynuclear Aromatic Hydrocarbons
The data was measured by scanning the substrate in steps of 200 µm using a rectangular aperture. The
spectra of the individual solutes are clearly recognizable in the figure.
The signal to noise ratio of the spectra was measured for the solute pyrene over a range of sample sizes.
The sample size that would just provide a identifiable spectrum was taken as the limit of detection. The
spectrum
