Specific Detectors in Gas Phase Chromatography

It is not possible to present all special detectors used in gas phase chromatography, but instead we will mention some recent applications. 

Among the various detectors specific for nitrogen, the NPD (Nitrogen Phosphorus Thermionic Detector) we will consider, is based on the following concept the eluted components enter a conventional FID burner whose air and hydrogen flows are controlled to eliminate the response for hydrocarbons. 

Chapter 3. CHARACTERIZATION OF CRUDE OlLS AND PETROLEUM FRACTIONS 

The collector contains an electrically-heated rubidium salt used as the thermionic source. During the elution of a molecule of a nitrogen compound, the nitrogen is ionized and the collection of these ions produces the signal. The detector is very sensitive but Its efficiency is variable subject to the type of nitrogen molecule, making quantification somewhat delicate. 

On leaving the column, the components enter a plasma functioning in identical manner to that described in article 2.2.6.3. All the atoms present emit their own specific emission spectra and can be detected and quantified. The sensitivity is excellent for carbon, hydrogen, and sulfur and average for nitrogen and oxygen. 

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