Hi so I'm using NMR to determine if my drug is dissociating back into the free acid from the Metal(L)3 chelated state but the -OH peak isn't showing up in the controls for free acid, or in incubated drug samples. As I cannot rely on the hydroxyl peak, is proton integration a reliable source for determining if dissociation occurs?
I'm not sure that I fully understand the question. If you can't see the hydroxyl signal in the free acid then integration is obviously not possible. I suppose the question is: why is the hydroxyl not visible in the free acid? It may be very broad or it could be part of a water signal if you have wet solvent. It could be exchanged if you use D2O or MeOD.
In any case, integration value for exchangeable protons are extremely unreliable, so I would not recommend using them for quantitative measurements.
Try to find other protons which may show different chemical shifts in coordinated and non-coordinated form; then you may be able to determine the relative concentration of your species of interest in (supposedly) equilibrium position.