The ability of amino acids/proteins to behave like zwitterions forms the basis for separating them using the following technique: (A) Gel filtration chromatography, (B) Ion exchange chromatography, (C) Isoelectric focusing, (D) Mass spectrometry
Answer is C. Isoelectric focusing is based on the isoelectric pH (pH at which a molecule carries no net charge). pH gradients created in the gel using polyampholytes. As there is no net charge, molecule stops moving during electrophoresis if they encounter their pI.