<unk>  is a compound with the formula<unk> . It is normally encountered as a gas with a characteristic pungent odor. Although<unk>  contributes significantly to the nutritional needs of the planet, the gas itself is caustic and can cause serious health damage. The United States Occupational Safety and Health Administration (OSHA) has set a 15-minute exposure limit for gaseous<unk>  of 35 ppm by volume in the environmental air and an  8-hour exposure limit of 25 ppm by volume. Exposure to very high concentrations of gaseous<unk>  can result in lung damage and death. Although<unk>  is regulated in the United States as a non-flammable gas, it still meets the definition of a material that is toxic by inhalation and requires a hazardous safety permit when transported in quantities greater than 13,248 L (3,500 gallons).<unk>  used commercially is usually named anhydrous<unk> . This term emphasizes the absence of water.  Because<unk>  boils at -33 °C, the liquid must be stored under pressure or at low temperature.  Its heat of vaporization is, however, sufficiently high that<unk>  can be readily handled in ordinary beakers in a fume hood.  "Household<unk> " or "ammonium hydroxide" is a solution of<unk>  in water.  The strength of such solutions is measured in units of baume (density), with 26 degrees baume (about 30 weight percent<unk>  at 15.5 °C) being the typical high concentration commercial product. Household<unk>  ranges in concentration from 5 to 10 weight percent<unk> . See Baumé scale.
Ammonia
Uric acid
Creatinine
Albumin
Potassium
Glucose
Diglyceride
Lactic acid