Question:

Why do anion exchange resins smell

Answer:

Anion exchange resins, especially strong base anion exchange resins in the hydroxide form, may emit odors such as a dead fish smell. The main cause is release of very low levels of amines from the resin (trimethylamine for Type I strong base resins).  Amines, such as trimethylamine, have a very low odor threshold (5 ppb) and will be smelled at levels well below the hazardous limits established by regulatory agencies. Trimethylamine is also released by decomposing fish, hence the association of the resin odor with a dead fish.

If desired, the amines can be quickly rinsed from the resin using deionized water before placing the resin into service.