resulting from the presence of a solute in the column eluent sensor cell is amplified and recorded. The sensitivity of the detector was similar to that of the katharometer i.e. about 1 x 10-6 g/ml. Unfortunately, the practical lifetime of this detector was also relatively short as it was eclipsed by both the FID and the argon ionization family of detectors subsequently introduced by Lovelock. The Emissivity Detector Another interesting early detector was the emissivity detector developed by Grant. an interesting and innovative extension of the flame thermocouple detector.  

mounting. D, metal stops for draught top,. E, selenium photo-cell. F, glass condensing lens. G, column inlet. H, column. I, column heating jacket. J, supports for reflector. L, metal reflector. M, stainless steel jet. N, 2 cm deep layer of porcelain beads. O, coal gas inlet. P, air inlet. Figure 10 The Emissivity Detector   It did not prove particularly popular at the time, but in recent years the concept has been revived and commercial detectors based on the emissivity concept of Grant are now available. The original detector was very simple in design and the original diagram of the device is shown in figure 10

nbsp; Virtually all the basic drugs contain nitrogen and thus can be specifically detected among a large number of other unresolved compounds not containing nitrogen. The Emissivity or Photometric Detector The emissivity detector or, the Flame Photometric detector (FPD), was described by Grant (10) in 1958 but as it could not compete in sensitivity with the ionization detectors, did not raise any commercial interest. The emissivity detector, however, has some unique properties that could make its response quite specific and giving it certain unique areas of application. It was originally used to differentiate aromatic from paraffinic hydrocarbons by measuring the luminosity that the aromatic nucleus imparted to the flame. Contemporary photometric detectors do not usually monitor

The system is very similar to that originally devised by Grant. The end of the capillary column is led into the flame jet where the column eluent mixes with the hydrogen flow and is burnt. The jet and the actual flame is shielded to prevent light from the flame itself falling directly on to the photo-multiplier. The base of the jet is heated to prevent vapor condensation. The light emitted above the flame, first passes through two heat filters and then through the wavelength selector filter and finally on to the photo-multiplier. The response of the

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