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This article in SSSAJ

  1. Vol. 30 No. 4, p. 450-453
    Received: Nov 16, 1965



Determination and Isotope-Ratio Analysis of Different Forms of Nitrogen in Soils: 2. A Simplified Procedure for Isotope-Ratio Analysis of Soil Nitrogen1

  1. H. H. Cheng and
  2. J. M. Bremner2



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 H2SO4). An aliquot of the digest is partially neutralized and treated in vacuo with alkaline hypobromiteiodide solution, and the N2 liberated by this treatment is analyzed by the mass spectrometer. This simplified procedure eliminates problems encountered in distillation and concentration of ammonium samples for N15 analysis and gives the same results as the customary procedure.

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