A mixture of two amino acids having pI $9.60$ and $5.40$ can be separated
A mixture of two amino acids having pI $9.60$ and $5.40$ can be separated
by adjusting the $\mathrm{pH}$ of the solution at $9.60$
by adjusting the $\mathrm{pH}$ of the solution at $4.20$
by adjusting the $\mathrm{pH}$ of the solution at $7.0$
by adjusting the $\mathrm{pH}$ of the solution at $7.5$.
Solution
Every amino acid exists exclusively as dipolar ion when the $\mathrm{pH}$ of the solution is equal to its isoelectric point (pI), hence at this $\mathrm{pH}$ it does not migrate to either electrode, while at other $\mathrm{pH}$, an amino acid migrates either to cathode or to anode depending upon its pI. Thus at $\mathrm{pH} 9.60$, amino acid with pI $5.40$ will exist as an anion and migrate to anode; while that with pI $9.60$ will not migrate to any electrode.
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