[nobOdy98]

Ok, so I am working for credit in a radiochem research lab and was given my first project. I am supposed to use a ligand and choose a Lanthanide and determine the K value via potentiametric titration. Here is the kicker, I was assigned a grad student who gave me a pile of papers and said go for it! Awesome right?

I need some help with the setup of the experiment. I am using water as my solvent right now and will be  moving to a water/methanol soln later. I have decided to run the experiment at an ionic strength of 0.05.
and I am using either Ce3+, Sm3+ or Tb3+ as my lanthanide.

Here is my plan as of right now (this is the part that I need help with):

Make a soln of 0.05 ionic strength containing my ligand (H2A), Ln3+ and water. Use appropriate base to titrate and use equivalence point to eventually determine the  equilibrium constant.

Here are some questions that jump into my mind when I am getting ready to set this up.

I am supposed to make the sodium salt of the ligand first, does that change anything?
What ratio of Ligand to Ln should I use?
What would be an appropriate base?
The Ln is in a solution of perchlorate, what do I do about that?