Gas Chromatography Detectors - The Katharometer Detector > Page 31

The detector consists primarily of two parts, the sensor and the associated signal conditioning electronics. The two parts can be integral or discrete. Although to minimize dispersion, the sensor should be situated as close to the column as possible. The electronic system can be situated some distance from the sensor if more convenient. Nevertheless, the signal must be transmitted in an appropriate manner to avoid any electrical interference that might provide extra noise or signal distortion. The associated electronics may contain an A/D converter to provide a binary output that can be addressed and acquired by a computer or the analog signal may be passed to a computer that has its own A/D converter. In general the sooner the signal is digitized the better, as digital data is far more immune to external interference than analog signals.


The Katharometer Detector

The katharometer was developed in the late 1940s for measuring carbon dioxide in the flue gasses produced from various types of industrial furnaces. A knowledge of the carbon dioxide content allowed the combustion conditions to be changed to improve burning efficiency. With the introduction of gas chromatography, its use as a possible GC detector was explored by Ray (11). T he sensor is a simple device and is depicted in figure 12.

Figure 12. The Katharometer Detector