HPLC

The Agilent 1100 Series Purification System is available for analysis and purification of proteins and peptides:

Reverse-phase columns separate peptides on the basis of hydrophobicity.
Reverse-phase is the principle type of column used in most single dimension LC and LC-MS/MS experiments.
Compounds stick to bind to the hydrophobic stationary phase in HPLC columns in high aqueous mobile phase and are eluted from the column with increasing organic mobile phase.
In the aqueous phase peptides bind to the hydrophobic column material through a hydrophobic interaction then are eluted according to relative hydrophobicity as the organic eluting buffer begins to disrupt these interactions.
Peptides are separated by running a linear gradient of the organic solvent.
The more hydrophobic the peptide the higher the organic concentration required to elute the peptide from the reversed phase column.

Peptide mapping on RP-HPLC with collection of peptide fractions.
QC analysis of purified peptides and proteins.
Purification of functionally active proteins and peptides. A full range of chromatography techniques are available including gel filtration, ion exchange, reversed phase and affinity,

Sample origin and type is helpful deciding appropriate HPLC separation conditions.
Knowledge of sample buffer is important because not all buffers are compatible with HPLC eg presence of detergents.
Sample must be free of any particulates or other insoluble material and should be filtered or centrifuged prior to injection.