This foundational study introduces Flow Induced Dispersion Analysis (FIDA) as a new method for characterizing noncovalent biomolecular interactions using only nanoliter sample volumes. FIDA works by analyzing the temporal variance of a detected analyte peak under pressure-driven (Taylor dispersion) flow in micrometer-sized fused-silica capillaries, so that binding is read out as a change in the analyte's apparent size as it forms a complex. FIDA was used to measure the diffusivities (hydrodynamic size) of both the free analyte and the bound complex, from which the noncovalent interaction is quantified. The authors present the approach as easy to implement and applicable to small, precious samples, establishing the basis for the FIDA technology later commercialized by Fidabio.