Solid phase extraction on reverse phase chromatographic media subjected to stresses expected for extraterrestrial...

Sample preparation techniques, such as solid phase extraction, will likely be required for in situ analysis of liquid samples collected from bodies in our Solar System that contain liquid, to concentration and desalt analytes of interest from the expected brines on these Ocean Worlds. Media to be used for these extraction procedures will have to survive the stresses of the long spaceflight required to reach these bodies, and remain functional once at that location. This work utilized tryptophan as an initial representative analyte to evaluate capture and desalting efficiencies in silica and polymeric reverse phase media, to determine how these solid phases might withstand stresses they could experience during deployment, including vacuum exposure, freezing, and heating/sonication treatments. Further experimentation on irradiation and long term freezing of media with an expanded array of analytes evaluated the utility of reverse phase media for this application. Kromasil® C-18 silica particles performed well, showing no loss in capture or desalting efficiency for the initial stress treatments or irradiation, but long term freezing after irradiation caused issues with this media. Oasis® HLB polymeric particles performed better, with 100% capture efficiency and 90% recovery of the tryptophan analyte for all treated and the untreated media. Onyx C-18 guard cartridges, a reverse phase C-18 modified silica monolithic media, exhibiting 100% capture efficiency and >90% recovery of tryptophan for both untreated and treated monoliths but also had issues after irradiation and long term frozen storage. Chromolith® RP-18e silica monolithic guard cartridges showed issues with consistency and reproducibility. In expanding the list of analytes, the Oasis® HLB media showed the best performance, capturing more of the analytes tested and remaining fully functional through both irradiation and long term storage treatments. Other media with additional reverse phase capture characteristics were also evaluated but none performed as well on the selected analytes as the Oasis® HLB media.