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This modification allowed the transport medium itself to be used as the sample holder for the IR
measurement. The rotation of the plate was actuated by a signal from the detector, so that as a peak
began to elute, the plate was moved to a new collection position. When the elution of the peak was
complete, the disk moved on again, isolating the sample at a specific position at the perimeter of the
plate. The authors utilized a small-bore column and the eluent (flow rate 5 µl/ min) was allowed to fall
on the plate and evaporate. The eluent was also monitored by a UV detector, the signal from which was
used to identify the time the plate should be moved. The solvent was allowed to evaporate under
ambient conditions, or the evaporation could be assisted by the use of an infrared heater, directed on the
collection area.

After the chromatogram had been developed, and the spots were free from solvent, the light transmitted
through the sample and the plate was measured and the spectrum of each solute obtained. It is clear that
the system excluded the use of any solvent in which the halide was significantly soluble. Good
sensitivity was reported, but the minimum detectable mass or concentration was not precisely defined in
chromatographic terms. However the procedure (and, for that matter, the procedure of Kuehl and
Griffiths [3]) would probably be considered as little more than novel methods of fraction collecting and,
in fact, were really off-line procedures. Nevertheless, the results from these early workers encouraged
the transport concept to be examined further.

Raynor et al. [7] employed a similar interface to monitor the IR spectra of some polymer additives,
using super critical fluid chromatography. They used a heated transfer line that terminated 50 µm above
a potassium bromide window in a similar manner to that of Jino and Fujimoto. The sample
compartment was purged with nitrogen to reduce interference from water vapor and carbon dioxide.
The spectra were collected with the microscope in the IR transmission mode. The IR beam was stopped
down to an aperture of about 150 µm, or less, depending on the size of the deposit. The results obtained
from the separation of a mixture of different polymer additives are shown in Figure 8.2.