title: An ultra-micro method for the determination of total nitrogen in biological fluids based on Kjeldahl digestion and enzymatic estimation of ammonia.
abstract: An ultra-micro method for the determination of the total nitrogen-content of biological fluids and suspensions is described, based on a digestion in sulphuric acid and a enzymatic determination of the ammonia formed with glutamate dehydrogenase (EC 1.4.1.3). The proposed method yields the same results as the classical Kjeldahl procedure, but is less time-consuming. The detection-limit of the nitrogen, without loss of precision and accuracy, is much lower than in the original Kjeldahl procedure, and is in the order of 35 ng N per sample.
mesh_terms: D000641:Ammonia / Q000032:analysis*; D000818:Animals; D005969:Glutamate Dehydrogenase; D006801:Humans; D007202:Indicators and Reagents; D008832:Microchemistry; D009584:Nitrogen / Q000032:analysis*; D012709:Serum Albumin / Q000032:analysis; D013056:Spectrophotometry, Ultraviolet / Q000379:methods
chemical_list: D007202:Indicators and Reagents; D012709:Serum Albumin; D000641:Ammonia; D005969:Glutamate Dehydrogenase; D009584:Nitrogen