Attempt titrating an amino acid against a weak base and discover the number of dissociating (ionizable) functional groups in the amino acid.

Explanation

When an amino acid is dissolved in water , it exists as the dipolar ion or zwitter ion (i.e. hybrid ion) so can act as either an acid( proton donor) or a base (proton acceptor) . This is because it has two ionizable groups i.e.- `NH_(3)^(+)` and `-COO^(-)` shown below :

In some amino acids , R-group is non-ionizable e.g. glycine , but in some amino acids , even R-group is ionizable e.g. Glutamic acid , histidine ,etc.