Microchip nonaqueous capillary electrophoresis of saturated fatty acids using a new fluorescent dye

We demonstrate nonaqueous labeling and separation of the full range of short to long saturated fatty acids (C2 to C30) for the first time on a microfluidic device. A new fluorescent dye, Pacific Blue hydrazide, labels the carboxylic acid in a two-step, one-pot reaction to enable detection via laser-induced fluorescence at 405 nm excitation. Limits of detection for C10 to C30 acids range from 0.9 to 5.7 mu M. Fatty acids were successfully quantified in a sediment sample from the 'Snake Pit' hydrothermal system of the Mid-Atlantic Ridge, demonstrating the potential of this method to help characterize microbial communities through targeted biomarker analysis. Such a technique could also be utilized to differentiate between abiotic and biotic compounds in the search for life beyond Earth.