Dear Shelley,

You don't need to digest TBP in order to analyse REEs in the solution. There is an extension available for ICP-OES which can directly determine the concentration of metal present in organic samples. Contact your ICP supplier to confirm if they can supply the same for your model.

Dear Shelley,

you can choice from more than one ways

1- as Amit anand advised you

2- using conc sulfuric acid

or

using stripping methods

1- acidified water (0.1 mol nitric acid ) / organic phase 1:1 by volume through 3-4 stages (known volumes)

2- hot distilled water ~55 C (131 F) 1:1 by volume through 3-4 stages (known volumes)

3- distilled water ~ 1:1 by volume through 4-5 stages (known volumes)

best wishes

Ebrahim