Fatty Acid Analysis by Capillary Electrophoresis and Contactless Conductivity Detection for Future Life Detection Missions

Future life-detection missions will likely search for biosignatures within a wide range of organic compounds, including fatty acids. In order to determine such biosignatures, it is necessary to identify and quantify individual fatty acids present within a sample. In this study, we present a method using capillary electrophoresis coupled to contactless conductivity detection (CE-C⁴D) for the separation and detection of both saturated and unsaturated fatty acids after derivatization with N,N-diethylethylenediamine, triethylamine, and 2-chloro-1-methylpyridinium iodide at 40°C for 10 min. Operating conditions (background electrolyte, separation voltage, and temperature) were optimized to provide maximum separation of fatty acids, thereby allowing their identification and quantification. Using a background electrolyte of 2 M acetic acid in 45% acetonitrile, an optimal separation was obtained with a separation voltage of 10 kV and a capillary temperature of 15°C. The optimized CE-C⁴D method was used to analyze samples of the cyanobacterium Spirulina. Multiple fatty acids were detected in the samples, showing the potential of this method for detection of fatty acid biosignatures during future spaceflight missions.