With this method, nitrogen and phosphorus can be selectively detected with a sensitivity that is 104 times greater than that for carbon.
[citation needed] A concentration of hydrogen gas is used such that it is just below the minimum required for ignition.
A rubidium or cesium bead, which is mounted over the nozzle, ignites the hydrogen (by acting catalytically), and forms a cold plasma.
Excitation of the alkali metal results in ejection of electrons, which in turn are detected as a current flow between an anode and cathode in the chamber.
As nitrogen or phosphorus analytes exit the column, they cause a reduction in the work function of the metal bead, resulting in an increase in current.