What is a suitable process to eliminate an excess of pyridine from an aqueous solution?

I have a reaction in which pyridin is used as a reagent in excess. The resulting product is water soluble and an anion. Pyridinium there will act as a counter ion. Normally, when the product is soluble in organic solvents pyridine is removed by washing with HCl 1 M or with CuSO4 10%. What is the best way to achieve this when the product is water soluble in comparison? In the moment I would apply these strategies:


1. Applying vacuum and high vacuum until mass is constant (pyridinium salts can not be removed).
2. Setting the pH of the water phase slightly basic to pH 8-9 and (pyridinium pka = 5.2) and so multiple extractions with DCM/water.
3. Applying anionic exchange chromatography (Pyridin is washed through the column. Pyridinium is also replaced as a cation by a cation that is present in the mobile phase).


I am wondering if this is already the best possible approach or if you know of a means to remove pyridine more elegantly?


