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Some Less Common GC Detectors
Over the years between 1956 and 1980, a considerable number of novel GC detecting systems were developed and, at one time or another, each was strongly acclaimed by the enthusiastic inventor for some specific application. Very few of these detectors have survived and even fewer are still being manufactured and are commercially available. However, one or two have recently been rediscovered and found suitable for new areas of application. A selected number of this fairly large group of "lost detectors" will be briefly described to illustrate the large variety of sensing techniques that have been applied to GC detection.
The Thermionic Ionization Detector
Electrons produced by a heated filament can be accelerated by an appropriate potential so that they attain sufficient energy to ionize any gas or vapor molecules in their path. In 1957, the early days of gas chromatography, Ryce and Bryce [29,30] modified a standard vacuum ionization gauge to examine its possibilities as a GC detector. A diagram of the device is shown in figure 47.
Figure 47. The Ionization Gauge Detector