Abstract
We have endevoured to extend the application field for ion exchangers. Though the electrostatic force diminishes as the pH decreases, it was found that the adsorptive force of vitamin B_<12> to the ion exchange resin increased in spite of lower pH. This fact shows that ion exchangers can be applied not only for ion exchange reaction but also for physical adsorption. Some experiments were presented to prove that vitamin B_<12> might be adsorbed through hydrogen ion of the ion exchangers.
