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Determination and Isotope‐Ratio Analysis of Different Forms of Nitrogen in Soils: 2. A Simplified Procedure for Isotope‐Ratio Analysis of Soil Nitrogen
Author(s) -
Cheng H. H.,
Bremner J. M.
Publication year - 1966
Publication title -
soil science society of america journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.836
H-Index - 168
eISSN - 1435-0661
pISSN - 0361-5995
DOI - 10.2136/sssaj1966.03615995003000040016x
Subject(s) - kjeldahl method , chemistry , nitrogen , distillation , ammonium , sulfuric acid , ammonium sulfate , potassium , soil water , digestion (alchemy) , soil test , fractional distillation , environmental chemistry , inorganic chemistry , chromatography , environmental science , organic chemistry , soil science
Abstract A procedure for isotope‐ratio analysis of soil nitrogen is described which eliminates the ammonium distillation stage of the customary procedure. The nitrogen in the soil sample is converted to ammonium by Kjeldahl digestion without use of a catalyst, digestion being accomplished by heating the sample with sulfuric acid containing a high concentration of potassium sulfate (ca. 0.7g/ml of H 2 SO 4 ). An aliquot of the digest is partially neutralized and treated in vacuo with alkaline hypobromiteiodide solution, and the N 2 liberated by this treatment is analyzed by the mass spectrometer. This simplified procedure eliminates problems encountered in distillation and concentration of ammonium samples for N 15 analysis and gives the same results as the customary procedure.