【国外标准】 Standard Test Method for Total Nitrogen in Organic Materials by Modified Kjeldahl Method (Withdrawn 2019)

4.1 This test method may be used to determine the total nitrogen content of certain unknown organic samples, or to assay known nitrogen containing organic compounds.4.2 This test method may be used on organic materials in which the complete conversion of nitrogen to ammonium sulfate can be accomplished by digestion in a mixture of sulfuric acid, potassium sulfate, and mercuric oxide. It cannot be used on materials containing N–O, N–N linkages.4.3 This test method assumes that ammonia can be quantitatively measured by distillation from an alkaline solution into a measured volume of standard acid.1.1 This test method covers the determination of total nitrogen in nitrogen-containing organic compounds. This test method is not applicable for use on materials containing N-O, N-N linkages.1.2 The values stated in SI units are to be regarded as standard. The values given in parentheses are for information only.1.3  This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.NOTE 1: Another method of restricted application is given in Test Method D1013.