Core-shell silica@pyridyl conjugated microporous polymer as a stationary phase for high performance liquid...

Because of the advantages of good selectivity, high sensitivity, and fast analysis, high performance liquid chromatography (HPLC) has become one of the modern analytical techniques in wide application range, such as biological analysis, environmental detection, pharmaceutical and food inspection, agriculture and other fields. The stationary phase greatly decides the chromatographic separation performance, so the development of novel stationary phase is most important for HPLC.

Pyridyl conjugated microporous polymers (P-CMP) with one to four layers were modified on the surface of amino silica to obtain a novel core-shell material (SiO2@P-CMP) by the layer-by-layer assembly strategy and Chichibabin reaction. The relationship between the structure of SiO2@P-CMP and chromatographic performance was carefully investigated, and the retention mechanism was revealed. The interactions including π-π stacking, hydrophobic effect and hydrogen bond gradually enhanced with the increase of P-CMP layers on the silica surface. Compared with C18 column, SiO2@P-CMP columns displayed better separation selectivity for polycyclic aromatic hydrocarbons (PAHs). According to the relative retention values (α), the separation performance of SiO2@P-CMP columns (α = 1.144-1.884) for PAH isomers and other analytes was obviously better than that of C18 column (α = 0.998-1.487). Furthermore, the SiO2@P-CMP column with four layers was selected to separate different types of analytes (eight PAHs, four bisphenols, four estrogens and nine phthalates), and the peak order of analytes was different from that on the C18 column due to the influence of hydrogen-bonding and π-π interactions. The relative standard deviations (n = 10) of retention time and peak area on SiO2@P-CMP column were between 0.28 % and 1.98 %.

Pyridyl conjugated microporous polymer was introduced as the stationary phase for the first time in HPLC. The proposed column displayed better separation characteristics compared to Zorbax SB-C₁₈ column. It provided a new idea for the separation of small molecules and the development of chromatographic packing or extraction material.