title: The isolation of urea nitrogen and ammonia nitrogen from biological samples for mass spectrometry.
mesh_terms: D000641:Ammonia / Q000652:urine*; D013058:Mass Spectrometry; D009584:Nitrogen / Q000652:urine*; D014508:Urea / Q000652:urine*
chemical_list: D000641:Ammonia; D014508:Urea; D009584:Nitrogen