Process and apparatus for determining total nitrogen content by

Details Process and apparatus for determining total nitrogen content by Process and apparatus for determining total nitrogen content by

1995-06-07

1997-03-18

Soderquist, Arlen

Chemistry: analytical and immunological testing

Nitrogen containing

Total nitrogen determined

436 52, 436 53, 436106, 436115, 436155, 436159, 436160, 422 78, 422 80, 422 81, 422 89, G01N 3112, G01N 3300

Patent

active

056122250

ABSTRACT:
This invention provides a process for determining the nitrogen content of a sample involving (a) combusting the sample in a combustion reactor in the presence of oxygen, which oxygen is introduced into the combustion reactor in pulse form; (b) reducing the resulting combustion gases by flowing them in a flow of helium or other noble carrier gas through a Cu-containing reduction reactor; (c) performing the steps of (i) making anhydrous in a water trap the reduced gases, (ii) flowing the reduced gases through a gas-chromatographic column in order to carry out a gas-chromatographic separation of N.sub.2 from CH.sub.4 possibly present within the reduced gases, and (iii) removing CO.sub.2 from the reduced gases using a CO.sub.2 trap, with the proviso that step (i) immediately precedes step (ii); and (d) analyzing the resulting gases by detecting thermal conductivity. This invention also provides an apparatus for determining the total nitrogen content of a sample which apparatus has a combustion reactor, a device for introducing oxygen into the combustion reactor in pulse form, a reduction reactor, a device for trapping water, a device for removing CO.sub.2 from combustion and carrier gases, a thermal conductivity detector, and a gas chromatographic column upstream of the detector packed with a material suitable to separate nitrogen from methane possibly present within the combustion gases.

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