Standards
USP monograph Oxygen (not less than 99.0%)
USP Oxygen is the United States Pharmacopeia monograph for oxygen containing not less than 99.0% of oxygen (O2) by volume; its public USP-NF preview, cited as 2020, gives only this definition, and a separate monograph, Oxygen 93 Percent, covers oxygen made from air by the molecular sieve process.
What is public
The USP-NF DOI page for the monograph (DOI 10.31003/USPNF_M59550_02_01, cited as United States Pharmacopeia, 2020) shows the formula O2, the figure 32.00 and the CAS number 7782-44-7, and the definition: not less than 99.0% of oxygen by volume. The page is a preview marked as not official USP-NF content; the tests and the official current text are in the subscription USP-NF, so check them there before writing them into a specification.
How it compares
| Monograph | Production named in the public text | Oxygen content |
|---|---|---|
| USP Oxygen | Not stated in the public definition | Not less than 99.0% by volume |
| USP Oxygen 93 Percent | Molecular sieve process, from air | 90.0% to 96.0% by volume |
| Ph. Eur. 0417 Oxygen | Cryogenic distillation (EDQM) | Minimum 99.5% (EDQM) |
The US and European monographs for high-purity oxygen set different minimums: 99.0% in USP Oxygen and 99.5% in Ph. Eur. 0417, according to EDQM. A specification that names only USP Oxygen does not cover oxygen 93, which has its own monograph, USP Oxygen 93 Percent.
Where it is asked for
- In UNDP procurement, the technical documentation listed in REQ-OXY-001 (effective 1 January 2025) includes a certificate of analysis showing compliance with the International, US and European pharmacopoeias for oxygen purity.
- The same document notes that in the USA medical oxygen is regulated as a prescription drug by the FDA.
ULTRAOX SC and ULTRAOX ST PSA plants from Ultra Controlo state a purity of 94% (±1%) in their datasheets, which lies inside the 90.0% to 96.0% range of USP Oxygen 93 Percent and below the 99.0% minimum of USP Oxygen.
More questions
Is USP Oxygen the same as Ph. Eur. 0417 Oxygen?
No. USP Oxygen requires not less than 99.0% oxygen; EDQM states that Ph. Eur. 0417 has a minimum O2 content of 99.5%.
Does USP Oxygen cover oxygen from a PSA plant?
Not oxygen 93: oxygen produced by the molecular sieve process with 90.0% to 96.0% oxygen is covered by USP Oxygen 93 Percent.
Sources
- USP-NF monograph Oxygen, DOI page (read in a browser on 23 October 2026)
- USP-NF monograph Oxygen 93 Percent
- EDQM news on oxygen monographs 0417, 2455 and 3098
- UNDP, REQ-OXY-001 V01, Technical & Regulatory Requirements for Oxygen Plants (effective 1 January 2025), 5.2.1.3 and technical documentation list
- ULTRAOX SC and ULTRAOX ST datasheets, p. 2
Ultra Controlo figures come from its technical datasheets. Third-party facts were read at the source on the date shown.