Alternative mobile phases for enhanced chromatographic selectivity and increased sensitivity in peptide separations

Area of Science:

• Analytical Chemistry
• Biochemistry
• Chromatography

Background:

• Reversed-phase high-performance liquid chromatography (RP-HPLC) with acetonitrile and trifluoroacetic acid is standard for peptide separation.
• Current methods face limitations in resolution, necessitating changes in mobile phase or complementary separation mechanisms.
• Enhanced sensitivity and selectivity are crucial for complex peptide mixture analysis.

Purpose of the Study:

• To explore alternative mobile phase additives for improved peptide separation.
• To evaluate the impact of hydrochloric acid versus trifluoroacetic acid in RP-HPLC of peptides.
• To assess the utility of strong cation exchange chromatography for peptide mapping.

Main Methods:

• Separation of tryptic digests of cytochrome c using RP-HPLC with a C18 column.
• Utilized dilute hydrochloric acid as an alternative to trifluoroacetic acid in the mobile phase.
• Employed strong cation exchange chromatography on a Protein-Pak SP 8HR column.

Main Results:

• Replacing trifluoroacetic acid with dilute hydrochloric acid at the same pH yielded different and enhanced reversed-phase selectivity.
• Hydrochloric acid-based mobile phases offered increased optical clarity, leading to higher sensitivity at low ultraviolet wavelengths.
• Cation exchange chromatography demonstrated significantly different selectivity compared to reversed-phase methods.

Conclusions:

• The study expands peptide mapping options by introducing hydrochloric acid as a mobile phase additive.
• This approach provides additional selectivity, increased mass sensitivity, and improved spectral information.
• The findings are valuable for researchers seeking to optimize peptide separation and analysis.