Separation of Peptides and Protein Digests by Capillary Electrophoresis

Peptide analysis is routinely performed using reversed-phase liquid chromatography (RP-HPLC), which achieves separation based on hydrophobicity differences between peptides (1 ,2 ). Recently, however, capillary electrophoresis (CE) has increasingly been used for peptide analysis. In capillary zone electrophoresis (CZE), the separation mechanism is based mainly on differences in charge-to-mass ratios, and since peptides are amphoteric, they are ideally suited to electrophoretic analysis. The different separation mechanism of CZE has provided workers with an excellent complementary tool to HPLC. The provision of such a complementary separation mechanism is extremely useful in characterization of complex biological samples and, in particular, where purification of peptides and proteins is often done by preparative HPLC, such an orthogonal technique is essential for purity control (3 ,4 ).