Here (almost*) the same amino acid mixture is analyzed, using a different composition (a different pH) of the mobile phase. Here you see that ala and arg are well separated.

*Note that cysteic acid is not present in this mixture.

Note that in this analysis cysteic acid and aspartic acid (at 0.8 min) are not separated. The same is the case for alanine and arginine at 6.8 min.

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In conclusion, these examples show that for an optimal separation of all amino acids in an sample, the composition of the mobile phase (e.g. type of liquid and pH) is crucial. Above this, also the type of the HPLC column is crucial.

Amino acids are separated by a chromatographic technique, usually by HPLC (High performance liquid chromatography).

The second step is: Separation of the resulting amino acids.

Here you see two examples of output from HPLC analysis of a mixture of amino acids.

The second step is: Separation of the resulting amino acids.