Consider that you wish to separate a mixture of glutamate, glycine and lysine by ion exchange chromatography.

Using an anion exchange column at pH 5, which amino acid would you expect to elute first and which last?

pKa and pI values are as follows:

Glutamate: pK₁ = 2.19, pK₂ = 9.67, pK_R = 4.25, pI = 3.22

Glycine: pK₁ = 2.34, pK₂ = 9.62, pI = 5.97

Lysine: pK₁ = 2.18, pK₂ = 8.95, pK_R = 10.53, pI = 9.74