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.
(Postponed indefinitely)
NF24
Change to read:
Identification—
Prepare a gas chromatograph as directed in the
Assay, and inject USP Nitrogen 97 Percent RS and a sample of Nitrogen 97 Percent into the gas chromatograph. The retention time of the major peak in the chromatogram of the test sample corresponds to that in the chromatogram of the USP Nitrogen 97 Percent RS.
NF24
(Postponed indefinitely)
NF24
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.
Change to read:
Assay—
Proceed as directed in the
Assay under
Nitrogen. The peak response produced by the assay specimen exhibits a retention time corresponding to that produced by
the
USP Oxygen–Helium RSNF24 and is equivalent to not more than 3.0% of oxygen when compared to the peak response of the
USP Oxygen–Helium RS,
NF24 indicating not less than 97.0%, by volume, of N
2.
(Postponed indefinitely)
NF24
11