Typical EGD-EGA Apparatus

Just as it is almost impossible to represent a typical EGD-EGA apparatus, it is equally difficult to describe the wide variety of detectors that have been employed- Using the techniques listed in Table 8.2, the type of detector employed for each method is listed in Table 8.5. As can be seen, there are a number of different types of detectors used, from simple thermal conductivity detectors to more sophisticated ion current detectors in mass spectrometry. It is, of course, impossible to discuss each one in detail here, although the complete apparatus is described in certain cases. 

Thermal conductivity detectors have been discussed in detail by Ingraham (107), who also described their application to thermodynamic and kinetic measurements. In this same book. Lodding (4) describes the gas density detector as well as several ionization detectors, such as the argon ionization detector, the electron capture detector, and others. Flame ionization detectors have been described in detail by Brody and Chaney (108) and Johnson (109). The latter also discusses other types of detectors. Malone and McFad-den (110) described many different types of special identification detectors, such as those listed in Table 8.3. Numerous texts on gas chromatography describe a wide variety of detectors, many of them useful in EGD and EGA. 

Differential thermal gas analysis Elemental analysis (pyrochrom) Evolved radiactive gas Flame ionization detection (Thermal Evolution Analysis) 

Piezoelectric detection Photometric detection Pressure changes Pyrolysis-GC Specific gas detectors Specific ion electrodes 

Special identification detectors Thermal conductivity detector Thermal energy analyzer Temperature-programmed reduction Thermoparticulaie analysis Thermal volatilization analysis Thin-layer chromatography Titrimetry Volume changes 

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A typical EGD-EGA apparatus cannot be described because of the wide variety of detectors that are employed. If certain restrictions are placed on the latter, plus other operating parameters, a general type apparatus can be depicted, such as is illustrated in Figure 8.22. The pyrolysis unit may be a simple furnace or other thermal analysis device such as a thermobalance, DTA, DSC, or so on. A temperature programmer provides the rate of... 

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