Capillary Electrophoresis and Contactless Conductivity Detection: A Powerful Tool for in Situ Analysis of Samples from Ocean Worlds

Abstract

The search for life in our Solar System is one of the highest priorities at NASA. Because of the presence of liquid water in the Oceans Worlds such as Jupiter's moon Europa, and Saturn's moon Enceladus, these bodies could potentially harbor life and be the focus of future missions. Liquid-based analytical techniques are particularly attractive for in situ analyses on these locations, since the sample could be analyzed in its natural state (e.g., liquid water or melted ice). Capillary electrophoresis (CE) is a powerful liquid separation technique that has tremendous promise for in situ studies on Ocean Worlds. By using contactless conductivity detection (C4D) a wide number of charged species (both organic and inorganic) can be detected without the need of derivatization. This includes amino acids, which are powerful biosignatures in the search for life beyond Earth as well as inorganic salts that are of primary importance to biological activity and they also determine the thermo-physical properties of any liquid mixture. The characterization of the distribution of inorganic ions is essential to assess the habitability of an extraterrestrial environment and provide sample context for trace detection of amino acids. We are currently developing CE-C4D methods that would be suitable for flight implementation. The first method allows the simultaneous analysis of inorganic cations and amino acids relevant to astrobiology [1]. A second method for analysis of inorganic anions and organic acids is also being developed. The main goal is to use both methods with a single capillary in order to obtain detailed chemical composition of the sample with the simplest configuration possible. Standard mixtures including some of the most relevant analytes for planetary studies were selected and electropherograms for the separations of the positively and negatively charged analytes are presented in the Figure 1A and B, respectively. To demonstrate the potential applications of these methods we have analyzed relevant natural samples of varying salinity. Acknowledgments The research described in this abstract was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration. Financial support for this project was provided by The Planetary Instrument Concepts for the Advancement of Solar System Observations (PICASSO) Program.