Actinide Ion-Exchange Resin

[b3ni]

Hi, this is my first post so, don't be too harsh 

Well, I'm researching an article for college on the discovery of the actinide elements (Mainly the synthetic ones). I was wondering if anyone knew of the ion-exchange resin used the discoveries of Berkelium through to Mendelevium (I assume they are the same one, yet if they are not one will do). I have searched online and through various text books. Using a reaction that's referenced in many of Glenn Seaborg's books is
M³⁺_(aq)  + 3 NH₄R_(s) ↔ MR_3(s) + 3 NH₄⁺_(aq)

Yet I can't seem to find online a polymer of which ammonium would be eliminated. Does anyone know of the one used or one in general.

Thanks in advance.
B3ni

Edit Sorry I forgot to add, R represents the organic part of the resin and M represents the Actinide ion

[b3ni]

Well I've found it, Dowex-50 is used, if anyone was interested. Haha, unfortunetly I plan stick around here, so this may not be last you'll see of me. Hopefully my next topic may go somewhere.

[b3ni]

Well it turns out the exchangeable ion in Dowex-50 is a H⁺ ion, I'm not sure why he refferences a reaction with an ammonium ion, no wonder I got confused.