Detection of Organics by Gas Chromatography/Gas Phase Fluorescence (GC/GPF)

The GC-GPF (Gas Chromatography-Gas Phase Fluorescence) system will take a detection method capable of very high sensitivity (fluorescence) and combine it with a separation system, (GC), that has been used successfully on mission. This will produce a compact, light, and low power detector that provides high sensitivity. The instrument would be designed to detect fatty acids in extracts of planetary samples produced by the Extractor for Chemical Analysis of Lipid Biomarkers in Regolith (ExCALiBR) for in-situ life detection. ExCALiBR integrates traditional lipid analysis techniques into a microfluidic platform that uses minimal reagent volumes and concentrates organics for analysis, thereby increasing signal-to-noise ratios by orders of magnitude.

Functional groups of interest, in this case the carboxylic acid groups on fatty acids, are derivatized before separation. Such a derivatization is necessary for GC analysis of many types of compounds, including fatty acids, in order to provide sufficient volatility. Here, in addition to imparting a chemical selectivity, this derivatization attaches a fluorescence chromophore for sensitive detection. After derivatization, compounds are separated by GC and their fluorescence is detected as the gas stream passes through the GPF detector. Fluorescence is generally accepted as one of the most sensitive detection techniques available for analytical separation applications at this time.

Our project would: 1) Identify a derivatization procedure for fluorescently tagging carboxylic acids compatible with the thermal cycling and long-term stability requirements for planetary surface instruments. 2) Identify fluorescent tags that will allow suitable separation and detection. 3) Develop and demonstrate GC-GPF detection to a functional system based on laboratory-scale components. 4) Test the system with ExCALiBR extracts. We rate the initial TRL as 2. The final TRL as 4.

The detection of the molecular biosignatures of life is an important science goal for NASA’s mission. This technology would contribute to such detection on missions to Europa, Enceladus and Mars. More generally, the detection of organics would be relevant indicators of early solar system chemistry (comets, asteroids, and KBOs) and prebiotic chemistry (on Titan, Mars, and Europa/Enceladus). The detector will be designed to work with the ExCALiBR system for biomarker detection, but would also be readily adaptable to detection of other organics and/or other extraction systems.

This program is, as the solicitation states, "development of spacecraft-based instrument systems that show promise for use in future planetary missions". The detection of organics would be applicable to a variety of missions (the search for life, detection of prebiotic chemistry, and geochemical and solar system processes) and worlds (e.g. Mars, Europa, Titan, Asteroids, and Comets). Its size/eight would make it suitable for any class of missions. The solicitation gives as a criteria "the extent to which the proposed instrument system or subsystem is applicable to multiple Planetary Science missions". It could also contribute to missions in planetary geology, geochemistry, and astrobiology and meets the solicitation’s interest in "planetary and astrobiology science". Its low power/cost/weight makes it responsive to the solicitation emphasis on “small, low-mass, and low power consumption instruments”. More »