Rapid preparation of a phosphate-functionalized polyhedral oligomeric silsesquioxane hybrid monolithic column in...

The present study proposes a facile fabrication of a phosphate-functionalized monolithic extraction column via radical polymerization within an ionic liquid (IL) porogenic system, with the objective of enriching microcystins (MCs). The synthesis employed bis[2-(methacryloxyethyl)] phosphate (BMEP) as the affinity monomer, methacryloxypropyl polyhedral oligomeric silsesquioxane (POSS-MA) as co-monomer, poly(ethylene glycol) diacrylate (PEGDA, Mn∼575) as crosslinker, and azobisisobutyronitrile (AIBN) as initiator. The structural and morphological properties of the resulting monolith were systematically investigated using scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), Fourier transform infrared spectroscopy (FT-IR), and nitrogen adsorption-desorption isotherms. It is evident that the use of [C₈mim,BF₄] IL enhances the solubility of monomer and accelerates polymerization rate. The incorporation of phosphate group and rigid POSS skeleton endows the hybrid monolith with specific phosphate-guanidine recognition, hydrophobic interaction, hierarchical porous structure, and good mechanical stability, thereby enabling high extraction efficiency and fast mass transfer to MCs. Under the optimized conditions, the as-prepared monolith was utilized for capillary microextraction (CME) of MCs in surface waters, prior to their analysis by HPLC-MS. The analytical performance validation revealed sub-ppt detection limits (0.83-1.12 ng l^-1) with satisfactory recoveries (73.4-119 %) and relative standard deviations of 1.0-7.3 %. These findings thus demonstrate the advantage of phosphate-functionalized monoliths in application-specific CME.