Long story short, I neutralized a basic hydrolysis product by stirring it with ion exchange resin in the pyridinium form to exchange Na+ with pyridinium. Since the pH was neutral, I assume that all excess Na+ had adsorbed to the resin and pushed pyridinium (hydroxide) into the product solution. After evaporation of the water, solvent and pyridine, I'm left with a residue that looks a bit salty, and now I'm curious what percenatge of the weight is residual salt (possibly 0).
My question is, how can I confirm that the product has been thoroughly desalinated? I know that conductivity of a solution can determine its ionic strength, but my product exists as an ion, so that probably wouldn't be very helpful in this case. I know that the 1H NMR will look poorly shimmed when salts are present, without tuning the probe, but that seems rather qualitative and indefinite. I'm also aware of flame tests/AAS which can identify the presence of ions/elements by color, but that seems a bit excessive. I suppose I'm hoping there's a Goldilocks solution to this problem (which isn't really an issue, it's not going to hold up the chemistry).
Any neat ideas?