The separation characteristics and performance evaluation of the silica-based poly(pentabromostyrene) stationary phase in capillary electrochromatography

A mixed-mode capillary column packed with silica-based poly(pentabromostyrene) particles (denoted as SiO2@pPBS) was prepared and applied to capillary electrochromatography (CEC) separation. With the presence of benzene rings and bromine atoms in the polymer chains, the SiO2@pPBS column provides reversed-phase/hydrophilic mixed-mode retention mechanism owing to hydrophilic, hydrophobic and π-π interactions between the stationary phase and various analytes, including alkylbenzenes, polycyclic aromatic hydrocarbons, nucleosides, phenols and anilines. In CEC mode, the separation behavior of charged solutes is not only related to the interaction with stationary phase, but also influenced by electrophoretic effects, which may lead to different selectivity compared to high performance liquid chromatography (HPLC). A column efficiency up to 1.22×105 N/m for p-chloroaniline was achieved. Besides, the RSDs of retention time of anilines for run to run (n=5), day to day (n=5) and column to column (n=3) were all less than 4.4%. Finally, the SiO2@pPBS capillary column was applied to the separation of coking wastewater with satisfied results. All the results demonstrated that the SiO2@pPBS capillary packed column with RP/HILIC mixed-mode has great application potential.