Nitrogen 97 Percent
» Nitrogen 97 Percent is Nitrogen produced from air by physical separation methods. It contains not less than 97.0 percent, by volume, of N2.
Packaging and storage— Preserve in cylinders or in a low-pressure collecting tank.
Labeling— Where it is piped directly from the collecting tank to the point of use, label each outlet “Nitrogen 97 Percent.”
note—Reduce the container pressure by means of a regulator. Measure the gases with a gas volume meter downstream from the detector tube in order to minimize contamination or change of the specimens.
The various detector tubes called for in the respective tests are listed under Reagents in the section Reagents, Indicators, and Solutions.
Identification— The flame of a burning wood splinter is extinguished when inserted into a test tube filled with Nitrogen 97 Percent. [note—Exercise caution.]
Odor— Carefully open the container valve to produce a moderate flow of gas. Do not direct the gas stream toward the face, but deflect a portion of the stream toward the nose: no appreciable odor is discernible.
Carbon dioxide— Pass 1000 ± 50 mL through a carbon dioxide detector tube at the rate specified for the tube: the indicator change corresponds to not more than 0.03%.
Carbon monoxide— Pass 1000 ± 50 mL through a carbon monoxide detector tube at the rate specified for the tube: the indicator change corresponds to not more than 0.001%.
Sulfur dioxide— Pass 1000 ± 50 mL through a sulfur dioxide detector tube at the rate specified for the tube: the indicator change corresponds to not more than 5 ppm.
Limit of nitric oxide and nitrogen dioxide— Pass 500 ± 50 mL through a nitric oxide–nitrogen dioxide detector tube at the rate specified for the tube: the indicator change corresponds to not more than 2.5 ppm.
Limit of oxygen— Not more than 3.0% of oxygen is present, determined as directed in the Assay.
Assay— Proceed with Nitrogen 97 Percent as directed in the Assay for Nitrogen. The peak response produced by the assay specimen exhibits a retention time corresponding to that produced by an oxygen–helium certified standard (see under Reagents in the section Reagents, Indicators, and Solutions) and is equivalent to not more than 3.0% of oxygen when compared to the peak response of the oxygen–helium certified standard, indicating not less than 97.0%, by volume, of N2.
Auxiliary Information— Please check for your question in the FAQs before contacting USP.
Topic/Question Contact Expert Committee
Monograph Kahkashan Zaidi, Ph.D.
Senior Scientist
1-301-816-8269
(AER05) Aerosols05
USP32–NF27 Page 1288
Pharmacopeial Forum: Volume No. 31(4) Page 1146