Chiral separation of fluorescamine-labeled amino acids using microfabricated capillary electrophoresis devices for extraterrestrial exploration

Abstract

Chiral separations of fluorescamine-labeled amino acids are characterized and optimized on a microfabricated capillary electrophoresis (CE) device. A standard mixture of acidic and neutral amino acids is labeled with fluorescamine in less than 5 min and the hydroxypropyl-β-cyclodextrin (HPβCD) concentration, temperature, and pH are optimized (15 mM HPβCD, 6 °C, pH<9) to achieve high-quality and low background chiral separations in less than 200 s. All four stereoisomers formed in the labeling reaction of the chiral dye with the chiral amino acids are typically resolved. At pH>9, isomerization of the dye chiral center is observed that occurs on the time scale of the chip separation. Typical limits of detection are ∼50 nM. These results demonstrate the feasibility of combining fluorescamine labeling of amino acids with microfabricated CE devices to develop low-volume, high-sensitivity apparatus and methods for extraterrestrial exploration.