Amino acids are essential components of numerous formulation. Health supplements can contain various amino acids and vitamins and require quantitation of each ingredients. Amino acids are very polar compounds with limited or no retention in reversed-phase chromatography. The most common approaches are reversed-phase chromatography with ion-pairing reagent and hydrophilic interaction chromatography (HILIC). Underivatized amino acids can be retained by combination of reversed-phase and cation exchange mechanism. These two mechanism were combined in Coresep 100 core-shell mixed-mode column. Method can be used for fast analysis of underivatized amino acids without ion-pairing reagent. Depending on the pH of the mobile phase they can exist in acidic, basic or zwitter-ionic form. At lower pH, amino acids are basic in nature and have the highest hydrophobicity. Four amino acids (SER, GLY, ALA, VAL and DOPA) were retained and separated within 2 minutes on core-shell mixed-mode column.
This high efficiency separation does not require special UPLC set up and can benefit from core-shell and mixed-mode approaches.