How do you measure small-molecule–protein binding in solution without immobilising anything? This Fidabio webinar introduces FIDA Lambda Dynamics, a Flow Induced Dispersion Analysis (FIDA) readout built for exactly that. By splitting the fluorophore's emission spectrum into two bands and taking their ratio, Lambda Dynamics detects the tiny spectral shifts that accompany binding, resolving changes as small as ~0.02% of signal, and on a Fida Neo measures binding affinity (KD) from picomolar to millimolar plus in-solution association and dissociation kinetics (kon, koff) without surface immobilisation, in agreement with SPR. It is an example of using FIDA to quantify small-molecule binding affinity and kinetics in free solution.