Which chromatography test fits best?

[Tyto alba]

Homework Statement

A purified protein fraction containing buffer with salt can be desalted by one of
the following techniques:
(1) Gel filtration chromatography
(3) Paper chromatography
(2) Affinity chromatography
(4) Thin layer chromatography2. The attempt at a solution
Well, the analyte contains salt (possible inorganic so the particles, ions will be small enough as compared to a protein) and protein (a large one) so SEC or gel filtration looks perfect.

But there's affinity chromatography too. Two things come to my mind:
1.having an antibody or enzyme in the stationary phase will definitely work at holding back the proteins
2. but there may be some non specific polar interactions between the protein and the ions, so... (1) 's the right one?

 

[DrDu]

With affinity chromatography you will have to use chaotropic solvents to remove the protein from the column. I wouldn't consider this desalting.

 

[epenguin]

Yes this is easier than your other question, and gel chromatography is the right answer. To elute your bound protein you would have to use either as mentioned chaotropic substance, or perhaps one with specific affinity for your protein. Then you'd probably want to get rid of that - E.g. by gel filtration!