How can I free-base my amine from TFA salt?

Hello everyone

I first used trifluoroacetic anhydride to react with my amine to form a protecting group, it should be something like the picture below. However, the 1H-NMR spectrum showed there was a peak at 11.5 ppm which didn't match the NMR spectrum described in paper. Therefore, I believe there's a CF₃COO^- group attached on amine group .

I have tried to extract my product from DCM/water several times, then evaporated the organic layer, and according to the reference it should work. unfortunately it didn't. Also I've seen that amberlyst-21 resin might help but we don't have it.

So, any suggestion how can I freebase my amine?