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 while various methods of manufacture were feasible when it was first introduced, recent revisions have restricted it specifically to oxygen produced by cryogenic distillation, with an O2 content specification of minimum 99.5%.
