Method The amino acids can be separated according their $pI$ ( → isoelectric point ) by electrophoresis:
The mixture to be characterized is deposited at 0. In the electric field, amino acids 1 and 2 migrate differently.
Amino Acids - having values of $ pI $ greater than the $pH$ of the electrophoresis buffer have a positive overall charge: They migrate to the negative electrode. - having values of $ pI $ less than the buffer $pH$ have a rather negative overall charge: They migrate to the positive electrode.