Peptide Impurities

The type of  "impurities" in a sample depends on whether or not the sample was purified by reverse phase HPLC. The following summarizes the difference between the two cases.

Impurities found in Non-Purified Peptides:

1. Deletion sequences
2. Truncation sequences
3. Incompletely deprotected sequences
4. Sequences modified during cleavage (reattachment of protecting groups at other locations on the peptide)
5. DTT (dithiothreitol)
6. TFA (trifluoroacetic acid)
7. Acetic acid
8. Peptides that have undergone side reactions such as proline isomerization or isoaspartimide formation, etc.

Impurities found in Purified Peptides:

1. Deletion sequences
2. Truncation sequences
3. Incompletely deprotected sequences
4. Sequences modified during cleavage (reattachment of protecting groups at other locations on the peptide)
5. TFA (trifluoroacetic acid)
6. Peptides that have undergone side reactions such as proline isomerization or aspartimide formation etc.

Peptides and Proteins homepage