Design of β-Alanine-Derived Novel C18 Stationary Phase Containing Embedded Urea and Amide Groups for the Separation of Versatile Analytes

Novel stationary phases have been emerging recently. A β-alanine-derived embedded urea and amide group-containing C18 phase (Sil-Ala-C18) was prepared for the first time. The media were packed into a 150 × 2.1 mm HPLC column, and the newly designed column was evaluated with the Tanaka and Neue test protocols in reversed-phase liquid chromatography (RPLC) separation mode. Moreover, it was characterized by the Tanaka test protocol in hydrophilic interaction chromatography (HILIC) separation mode. The new phase was characterized by elemental analysis, attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), and solid-state 13C cross-polarization magic angle spinning (CP/MAS) NMR spectroscopy at variable temperatures. The chromatographic evaluation involved very good separation of nonpolar shape-constrained isomers, polar and basic compounds in RPLC, and highly polar compounds in HILIC compared to the commercial reference columns. The Sil-Ala-C18 phase was able to separate the challenging β- and γ-isomers of tocopherol. The phase was also successfully applied for the separation of the isomers of tocopherol (vitamin E) and capsaicinoids from real samples of chili peppers (Capsicum spp.) in RPLC and ascorbic acid (vitamin C) in HILIC.