As I read in papers, before doing the radioimmunoassay (RIA) to detect thyroid hormones such as T3, we should free the hormones from binding the carrier proteins like thyroxine-binding protein (TBG) and albumin for higher accuracy. And 8-Anilino-1-naphthalenesulfonic acid (ANS) is one of the most widely used chemical reagents that can do that liberating purpose.

I searched several papers, however, they did not describe how ANS could do that such function?

Is it like a competitve substance that goes into protein and occupies T3 binding site? Or it will change the structure of the protein? Or something else...

If anyone has the explanation or documents/papers/books related to this issue, please share to me.

Thank you very much.