How can you measure binding kinetics (kon and koff) in solution without immobilising your protein on a surface? In this Fidabio webinar, FIDA inventor Henrik Jensen shows how Flow Induced Dispersion Analysis (FIDA) determines in-solution association and dissociation rate constants using a capillary-mixing (CapMix) assay: the two binding partners react only inside the capillary, and controlling the flow pressure sets the reaction time, shifting the binding curve away from equilibrium to reveal the kinetics. Because everything happens in free solution, there is no surface mass-transport limitation, regeneration step or non-specific-surface artefact, and the measured rate constants agreed with surface plasmon resonance (SPR). The webinar also introduces FIDA Lambda Dynamics for small-molecule–protein interactions, with sample-quality readouts (aggregation, size, viscosity) captured in every measurement from nanolitre samples. It is an example of using FIDA to measure binding affinity and kinetics under native, in-solution conditions.