Sometimes it is good to know kinetics of binding reaction in addition to dissociation constant. Different reactions with the same KD values could be intrinsically contrasting, one is fast-on/fast-off and the other is slow-on/slow-off reaction. Real time monitoring of binding event using surface plasmon resonance (SPR) lets us understand what is really going on. We use SPR method for initial detection of the specific interaction as well as precise quantification of kinetics.