Page 159 - Tandem Techniques
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Examples of the use of the device to identify some drugs of abuse are shown in Figure 4.8. The sample
was separated on a GC column employing normal development techniques, and the spectra taken of the
peaks as they were eluted through the light pipe. It is seen that the spectra that are obtained would be
perfectly satisfactory for solute identification.
Figure 4.8
Spectra Taken from a GC/IR Analysis of Some Drugs of
Abuse Employing the Perkin Elmer Light Pipe Interface.
Courtesy of the Perkin Elmer Corporation
Another typical example of the value of the instrument is for the analysis of the essential oils of basil. A
sample of the oil was obtained by a supercritical fluid technique. Superfluid extraction is now a
common method for obtaining samples of essential oils from botanical tissue. It has become popular
due to it being chemically 'gentle' and does not readily cause the degradation of thermally labile
materials. In the example given, the herb basil was extracted with liquid carbon dioxide at 60°C and
250 atmospheres pressure. The extract, a solution of the essential oil in liquid carbon dioxide, is
decompressed through a length of silica capillary into
