Column-friendly reversed-phase high-performance liquid chromatography of peptides and proteins using formic acid with sodium chloride and dynamic column coating with crown ethers.

Reversed-phase high-performance liquid chromatography of proteins, traditionally carried out with strong acids like trifluoroacetic acid or phosphoric acid, which can damage reversed-phase columns, can be performed with excellent results using the far milder formic acid in the presence of salt. For certain separations, dynamic coating of the column with crown ethers can bring added resolution. Examples given are for peptides from a digest of methionine growth hormone, protein separations from whey proteins containing alpha-lactalbumin and the beta-lactoglobulins A and B, and bovine and porcine insulins. The separation of methionine-growth hormone from growth hormone is also described.

Formic acid as a milder alternative to trifluoroacetic acid and phosphoric acid in two-dimensional peptide mapping.

In reversed-phase chromatography of peptides, formic acid has been shown to successfully replace the stronger traditional trifluoroacetic and phosphoric acids. Detection of non-aromatic peptide at lower wavelength is not impaired and being volatile the acid is easily removed, enabling further studies of the peptides. Also in ion-exchange chromatography (the first step of a two-dimensional approach) formic acid works well with a sulphonic acid ion-exchange resin.