title: Control and modification of methods for determination of  15 N in biological material.
mesh_terms: D000388:Air; D000596:Amino Acids / Q000032:analysis; D000641:Ammonia / Q000032:analysis; D001706:Biopsy; D002852:Chromatography, Ion Exchange; D006801:Humans; D066298:In Vitro Techniques; D009132:Muscles / Q000032:analysis; D009584:Nitrogen / Q000032:analysis*; D009587:Nitrogen Isotopes; D013057:Spectrum Analysis
chemical_list: D000596:Amino Acids; D009587:Nitrogen Isotopes; D000641:Ammonia; D009584:Nitrogen