Low-Temperature Microchip Nonaqueous Capillary Electrophoresis of Aliphatic Primary Amines: Applications to Titan Chemistry

Titan, the moon of Saturn with a thick atmosphere and an active hydrological cycle, is considered the best target in the solar system for the study of organic chemistry on a planetary scale.  Liquid-based methods may provide more information about Titan organic samples compared to pyrolysis and gas-phase techniques, and organic solvents in particular could be utilized to perform analysis of Titan samples at temperatures approaching those of the Titan surface (90 K).  Micro total analysis systems (µTAS) that employ liquid phase techniques such as capillary electrophoresis and ultrasensitive laser-induced fluorescence detection offer a unique solution to in situ analysis of complex organics on Titan.  We demonstrate microchip non-aqueous capillary electrophoresis (µNACE) analysis of primary aliphatic amines (C1-C18) in ethanol down to -20 °C as a first step in adapting microfluidic protocols for in situ analysis on Titan.  Limits of detection ranged from 1.0 to 2.6 nM, and we identified both short-chain (C2-C4) and long-chain (C15, C16) primary amines in Titan aerosol analogue (tholin) samples; new amines were also detected in a tholin sample exposed to oxygen and liquid water.  This preliminary work validates the sensitivity and efficacy of microfluidic chemical analysis of complex organics with relevance to Titan aerosols and surface deposits.