Frontal affinity chromatography is a powerful, underappreciated technique for the qualitative (screening) and quantitative (K d determination) evaluation of biological interactions. Its development has been previously hampered by its sample consumption, limited throughput, and lack of dedicated instrumentation especially at a miniaturized scale. This work describes two original experimental devices allowing nano-frontal affinity chromatography titrations (nano-FAC) to be automatically implemented in the time-saving staircase mode. The first nano-FAC system utilizes a capillary electrophoresis device (7100 CE Agilent system) in the pressurization mode with in situ UV detection. The second nano-FAC experimental setup implements a nano-LC device (Ultimate 3000 Thermo) modified with a 10-port valve equipped with two superloops (loop volume, 5 μL) operating alternatively and automatically in a single run. The benefits and drawbacks of each approach are exemplified using two model protein−ligand interactions (concanavalin A−mannose and concanavalin A−glucose). The two methods result in concordant dissociation constants (K d ) and number of active site (B act ) values, obtained in a fully automated manner, with low sample consumption and good throughput.

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