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The b–ray ionization detector was also introduced by Boer [9] in 1956. This was the first ionization detector that utilized a radioactive source and the design of the detector is shown diagramatically in figure 9. It consisted of a reference cell, through which pure carrier gas passed, and a sensor cell, which carried the column eluent. Each cell contained a 90strontium b emitting source that the three stage fission terminating in the stable atom of 90zirconium.

The ionization currents formed (collected by appropriate electrode potentials) are arranged to oppose one another and consequently any variation in pressure or temperature of the two cells will be balanced out. The differential signal 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.