Nitrogen

• BPNitrogen
• JPNitrogen
• Ph. Eur.Nitrogen
• USP–NFNitrogen

Azote; nitrogenium; E941

Nitrogen · [7727-37-9]

UNII N762921K75 · PubChem CID 947

N2 · 28.01

Propellant / inert gas

Typical concentrations: — · Dosage forms: Sterile (parenteral/ophthalmic)

Used as an inert gas to displace air (oxygen) from the headspace of ampoules, vials and other containers and to blanket solutions during manufacture of oxygen-sensitive products. It is also used as a compressed-gas propellant in some topical and nasal aerosols and pump-type sprays, and liquid nitrogen is used for freezing, cryogenic milling and storage of biological materials.

A colourless, odourless, tasteless, non-flammable gas that does not support combustion. It makes up about 78% by volume of air.

Boiling point

−195.8 °C

Melting point

≈ −210 °C

Critical temperature

≈ −147 °C

Density (gas)

≈ 1.25 g/L at 0 °C and 101.3 kPa

Solubility

very slightly soluble in water and ethanol

Purity

not less than 99.0–99.5% v/v, depending on pharmacopoeia

Chemically inert under normal conditions. Store in suitable, properly labelled high-pressure cylinders (or cryogenic vessels for liquid nitrogen) in a cool, well-ventilated place.

Generally compatible with pharmaceutical materials. It reacts only under extreme conditions, for example with lithium and some other reactive metals.

Produced by fractional distillation of liquefied air, or on site by pressure-swing adsorption or membrane separation of air.

Non-toxic, but a simple asphyxiant: it can displace oxygen in enclosed or poorly ventilated spaces, causing loss of consciousness and death without warning signs. Liquid nitrogen causes severe cold burns, and its rapid evaporation can over-pressurise closed containers.

Handle cylinders according to compressed-gas safety rules: secure them upright, use proper regulators and ensure good ventilation; oxygen monitoring is advisable where large volumes are used. Wear insulated gloves and a face shield with liquid nitrogen.

GRAS listed. Accepted as a food additive in Europe (E941). Included in the FDA Inactive Ingredient Database (injections; aerosols and other preparations) and in parenteral and non-parenteral medicines licensed in Europe.

Argon; carbon dioxide; nitrous oxide; air, medical.

Nitrogen used in contact with sterile products should be filtered through a sterilising-grade gas filter at the point of use. The effectiveness of headspace flushing should be verified by measuring residual oxygen in the filled containers.