Fabrication of fluorinated and covalently self-crosslinked poly(ionic liquid)s modified silica gel and its application in analysis of cold medications and food components.

Background: Self-crosslinked poly(ionic liquid)s (CPIs), a subset of ionic liquids, are emerging functional polymeric materials with broad applications in catalysis and sensor technology. However, there are scant reports on the use of CPIs as high-performance liquid chromatography (HPLC) stationary phases. Fluorinated materials, noted for their unique physicochemical properties, have recently drawn interest in purification and separation fields.

Results: In this work, self-crosslinked poly(ionic liquid)s were first employed to prepare a stationary phase (Sil-CPIs) for HPLC, and fluorine functionalization (Sil-CPIs-F) was achieved with 1H,1H,2H,2H-heptadecafluorodecyl acrylate (PFOEA).The impact of chromatographic conditions on retention demonstrated that both Sil-CPIs and Sil-CPIs-F could operate in a multimodal manner, with various analytes (including nucleobases, organic acids, and sulfonamide drugs) being effectively separated under different modes. Outstanding repeatability (RSD ≤0.67 %) and column efficiency (127,010 plates/m) were attained. Fluorine functionalization enhanced the separation performance of the poly(ionic liquid)s stationary phase, endowing it with superior selectivity and separation efficiency towards phenolic isomers and complex samples. Thermodynamic investigations revealed the differences in the retention mechanisms of Sil-CPIs and Sil-CPIs-F, while the linear solvation energy relationship (LSER) more specifically indicated that fluorine modification intensified dipole-dipole interaction and hydrophobic effect of Sil-CPIs. The column with better performance was used to detect chlorpheniramine maleate in pediatric cold medicine and dehydroacetic acid in 6 food samples (including bread, dessert, pastry, instant noodle seasoning packet, fruit and vegetable juice, and pickled turnip), with recovery rate ranging from 99.4 % to 104.67 %, meeting the detection requirements for actual samples.

Significance: This study confirms the modifiability of self-crosslinked poly(ionic liquid)s stationary phase with 3D reticulated structures, and demonstrates that the introduction of fluorinated monomer can enhance the comprehensive separation capabilities of Sil-CPIs. The potential application value of Sil-CPIs-F in the analysis of multi-component samples and actual detection has been highlighted.