Quantitative, compositional analysis of trace amino acids in icy moon analogues with a microcapillary electrophoresis laser-induced fluorescence detection system

Enceladus’s jet activity, Europa’s putative plume activity, and the evidence supporting global subsurface oceans have made them high-priority targets for future NASA missions. In situ analysis of organic molecules in the jets/plumes or subsurface oceans of these icy moons would provide relevant, detailed information on formation, habitability, and on-going planetary processes of celestial bodies and could provide the first evidence of the potential for extant life beyond Earth. Microcapillary electrophoresis with laser-induced fluorescence (µCE-LIF) enables highly-sensitive, automated, quantitative, compositional analysis of organic molecule monomers and short polymers and can achieve a sub-parts-per-trillion limit of detection. Portable Mars Organic Analyzer prototypes have been built and field tested and the Enceladus Organic Analyzer and Microfabricated Organic Analyzer for Biosignatures prototypes are under development as potential instruments for missions to Enceladus or Europa. Here, high-resolution separations of amino acids contained within icy moon analogue solutions of sulfuric acid, carbonic acid, sodium carbonate, and magnesium sulfate were obtained using a benchtop µCE-LIF system. Separations were improved by dilution, pH regulation, and chelation of cations with EDTA. Also, a sample taken from Champagne Geyser, a CO2-driven geyser at Chaffin Ranch, Utah, was analyzed for amino acids and found to contain leucine, valine, serine, alanine, and glycine. Alanine and glycine were quantified via a standard curve at 80.1 ± 0.8 µM and 900 ± 100 nM, respectively. This work represents a significant step forward for the liquid-based µCE-LIF analysis of small organic molecules and biopolymers for future space missions to icy bodies like Enceladus and Europa.