GC-MS Analysis of Contaminants in Breathing Oxygen

Abstract

Oxygen used for flight crews and for extra-hospital therapies is kept in vacuum containers and maintained as liquid phase (LOX) until use; by using this procedure, the weight of the breathing apparatus is reduced, thus extending breathing oxygen availability and improving safety by using atmosphere pressure sampler.

On the other hand, because of its low boiling point (−183°C), during storage and distribution, LOX shows continuous evaporation with a constant increase in pollutant concentration obtained in the LOX production.

Therefore, LOX is subjected to a strict quality control to evaluate the contamination levels from production until its use.

In this study, an analytical procedure has been optimised to measure the main LOX contaminants (freon, chlorinated solvents, light hydrocarbons, CO₂, CO, and N₂O) based on a single technique (GC-MS) and two chromatographic columns (Poraplot Q/HT and HP-Plot molecular sieve 5 A). The proposed method is an improvement in terms of time as well cost of analysis and selectivity with respect to the present methods based on three chromatographic techniques (GC-ECD, GC-FID, GC-HID) and four different columns.

Keywords:

• Breathing oxygen
• CH₄
• chlorinated solvent
• CO
• CO₂
• freon
• GC-MS-SIM
• HP-PLOT molecular sieve 5 A
• light hydrocarbons
• LOX
• N₂O
• Poraplot Q/HT

Notes

^a Yes = separated and detected; No/D = not detected; No/S = not separated.