|Research on automation of a reductive dissolved organic nitrogen analyser|
Le Poupon, C.; Lin, R.G.; Benaim, J.Y.; Merks, A.G.A. (1997). Research on automation of a reductive dissolved organic nitrogen analyser. Oceanol. Acta 20(2): 349-358
In: Oceanologica Acta. Elsevier/Gauthier-Villars: Montreuil. ISSN 0399-1784, more
|Authors|| || Top |
- Le Poupon, C.
- Lin, R.G.
- Benaim, J.Y.
- Merks, A.G.A.
The accurate classical batch method of Duursma (1961), based on the conversion of Dissolved Organic Nitrogen (DON) into NH3, is used as a basis for a new automatic DON analyser. After testing different possibilities through mechanical automation of the original batch technique, in which the conversion is preceded by the degassing of NH3 and drying of the sample, the procedure of autoanalyses has been selected. This procedure was simplified to the extent that a compact unit could be constructed, which would easily be applicable on board ship. The automatic method has a conversion phase in which in principle only DON is dissociated to NH4+, whereas both NO2- and NO3- are not reduced. This requires selective conditions and particularly high silver purity for the reactor. Consequently, a total reduction, including NO2- and NO3- is also possible, applying an efficient metal catalyst. Using distilled water, the accuracy of the method is at the level of 3 µM (0.05 mg N/l), whereas the percent conversion of DON into NH3 is estimated between 80 and 100 %, depending on the applied reference compounds. The method is applicable to both fresh and sea water.