The European Pharmacopoeia (Ph. Eur.) currently includes two monographs on oxygen: Oxygen (0417) and Oxygen (93 per cent) (2455).
Oxygen (0417) was drafted over 50 years ago and covers oxygen produced by cryogenic distillation, with an O2 content specification of minimum 99.5%.
Oxygen (93 per cent) (2455), was first published in the Ph. Eur. in 2010. This monograph covers oxygen produced by a concentrator that removes the nitrogen from ambient air using a pressure swing adsorption plant (PSA).
At the time of publication, the plants available on the market utilised a single-stage adsorption process which did not remove any argon from the air being processed. Advances have since been made in the design of PSA oxygen concentrators and two-stage PSA plants capable of producing oxygen with a nominal content of 98.0 per cent are now available.
This prompted the decision to elaborate a new monograph, Oxygen (98 per cent) (3098), as the ongoing COVID-19 pandemic has increased the demand for oxygen worldwide (by as much as a factor of 10).
However, the main issue appears to be the distribution systems in place within healthcare facilities rather than the actual availability of oxygen supplies. Recourse to a PSA plant provides healthcare facilities that do not have access to oxygen produced from cryogenic distillation of air, e.g. field hospitals, with an alternative source of oxygen…