Anion exchange resins, in general but especially strong base anion exchange resins in the hydroxide form, may release odors such as a dead fish smell. The main reason is the release of very low levels of alkyl-amines from the resin (i.e.: trimethylamine from Type I strong base resins). Trimethylamine is also released by decomposing fish, that is why it smells like a dead fish. Amines, such as trimethylamine, have a very low odor threshold for the human sesitivity (5 ppb) and will be smelled at levels well below the hazardous limits established by regulatory agencies.

The amines can be quickly rinsed from the resin using deionized water before placing the resin into service. Another option is to select a Type II strong base anion exchange resin which uses a dimethylethanolamine functional group but with less exchange capacity.