Those anion exchange products with functional groups which are not capable of splitting neutral salts to form corresponding free bases, Weak base anion exchange resins have a much higher (three to four times higher) regeneration efficiency than their strong base counterparts, but can only exchange mineral acid anions such as sulfate, chloride, and nitrate. The anions associated with weak acids, such as carbonates, bicarbonates, silicates, and organic acids, for example, cannot be removed with weak base anion exchange. SEE ALSO free base form.