Preparation and application of a novel dendrimer modified silica reversed phase/hydrophilic interaction mixed-mode...

A novel dendritic mixed-mode stationary phase (Sil-BD-AFT) with the properties of reversed phase and hydrophilic interaction modes was designed and synthesized. The stationary phase and its intermediates were characterized by Fourier Transform Infrared Spectroscopy (FT-IR), Thermogravimetric Analysis (TGA), and Elemental Analysis (EA). The characterization results showed that the dendritic polymers were successfully grafted onto the silica particles. The performance of the stationary phase was evaluated using various analytes, such as alkylbenzenes, polycyclic aromatic hydrocarbons (PAHs), positional isomers, nucleosides, alkaloids, halogenated benzenes, anilines, and phenols. The stationary phase exhibited outstanding separation efficiency for these compounds under the separation modes of reversed phase liquid chromatography (RPLC) and hydrophilic interaction liquid chromatography (HILIC). Furthermore, a comparison with commercial columns demonstrated that Sil-BD-AFT, with its mixed-mode separation capability, provided superior separation performance for structurally complex analytes such as anilines, phenols, and alkaloids. The effects of mobile phase composition and column temperature to retention time were examined. Investigation of the retention mechanism was carried out using the Van't Hoff equation and the Abraham Solvation Parameter Model, which revealed that π-π interaction, dipole-dipole interaction, hydrogen bonding, and hydrophobicity are the primary modes for chromatographic separation. The Van Deemter equation was employed to investigate the impact of flow rate to column efficiency. The prepared column exhibited excellent repeatability through the evaluation of chromatographic behaviors of multiple consecutive injections. Furthermore, the prepared chromatographic column can be further applied to detect bisphenol A in bills and phthalate esters in plastic wrap, respectively. The results open new avenues for the chromatographic separation of diverse analytes using dendrimers based mixed-mode stationary phases.