A Volatile Organics Concentrator for Use in Monitoring Space Station Water Quality

The process used to identify, select and design an approach to the isolation and concentration of volatile organic compounds from a water sample prior to chemical analysis in a microgravity environment is described. The Volatile Organics Concentrator (VOC) system described in this paper has been designed for attachment to a gas chromatograph/mass spectrometer (GC/MS) for analysis of volatile organics in water on Space Station.

In this work, in order to rank the many identified approaches, the system was broken into three critical areas. These were gases, volatile separation from water and water removal/GC/MS interface. Five options involving different gases (or combinations) for potential use in the VOC and GC/MS system were identified and ranked. Nine options for separation of volatiles from the water phase were identified and ranked. Seven options for use in the water removal/GC column and MS interface were also identified and included in overall considerations.

The final overall recommended concept for breadboard VOC testing utilizes an XAD® solid sorbent tube for collection with subsequent transfer utilizing nitrogen gas through a Nation® dryer tube coupled to a Tenax® secondary sorbent tube, then to a gas Chromatograph with an open split MS interface.