Analysis of Organic Biomarkers Using Integrated Microchip Capillary Electrophoresis Systems for In Situ Extraterrestrial Investigations
Microcapillary electrophoresis (mCE) coupled with laser-induced fluorescence (LIF) detection enables rapid, automated, and extremely sensitive analyses of organic biomarkers (down to 70 pM or sub pptr). I present recent work expanding compound class coverage of mCE-LIF to include amines, amino acids, dipeptides, aldehydes, ketones, carboxylic acids, and polycyclic aromatic hydrocarbons. A first- generation device enables automated sample processing and analysis of amino acids. Optimization of microvalve layout and operational protocols for contamination-free rapid microfluidic processing leads to the development of a set of design rules. Based on these rules, I present the development of a programmable microfluidic device that enables rapid automated fluorescent derivatization, serial dilution, spiking with standards, and mCE analysis of all desired classes of molecules. Storage conditions of reagents are optimized and characterized, including hydrolysis kinetics of the amine-reactive fluorescent probe Pacific Blue succinimidyl ester. Reagents stored on-chip in the solid form and reconstituted prior to analysis yields automated on-chip sample processing results from the hibernation-state system that are comparable with manual results (down to 3% difference). This work represents major technological advancement in microfluidic chemical analysis and miniaturization of supporting hardware toward in situ robotic missions.