Check the original data from the 'plutonium bomb' project in the 1940's.  I think they used EDTA (if memory recalls) in the 'purex' project.

Seawater?  I have no idea!

Hi Prof. Neagle

Thank you very much. Actually, I am intending to preconcentrate Th and U from seawater in ultratrace range for determination.

Not a professor. EDTA will chelate Ca and Mg which are commonly found in seawater.  Thus, preconcentration is a good idea, but Ca and Mg may also be pre-concentrated.

You can only experiment and evaluate the results!

Dear Dr. Neagle

Thanks a lot. As you know, very high background is not preferred in many detection techniques. Hence, removal of saline background (Na,K, Cl, Ca, Mg, ..) is a mandatory pretreatment step. In this context, selective separation and preconcentration of heavy metal ions is appropriate with the help of some chelating agents such as APDC. Thanks a lot again.