Preparation of boronate-modified larger mesoporous polymer microspheres with fumed silica nanoparticle and toluene as synergistic porogen for selective separation of sulfonamides

Abstract

Larger mesopores can effectively reduce the diffusion resistance of target molecules in microspheres. Therefore, the photoinitiated suspension polymerization was used to fabricate a novel mesoporous polymer microsphere (MPM), in which large macropores resulted from the synergy of fumed silica nanoparticle as solid porogen and toluene as auxiliary porogen. The spherical MPM had 35.9 nm of larger mesopores and was suitable for solid phase extraction (SPE) adsorbent. To improve the selectivity and adsorption capacity, the MPM was first grafted with polyethyleneimine as amplifier, and further modified with boronic acid moieties. The successful synthesis of the boronate-modified MPM (BMPM) was confirmed by detailed characterization. Due to the combination of B-N coordination and hydrophobic (or π-π) interaction, the resultant BMPM exhibited excellent adsorption performance for nitrogen-containing sulfonamides, which was successfully fitted with Langmuir, pseudo-first-order and pseudo-second-order kinetic models, respectively. Therefore, the BMPM as SPE adsorbent was used for enrichment and separation of sulfonamides. The BMPM-based SPE process was optimized in detail, and combined with high performance liquid chromatography (HPLC) analysis for simultaneous determination of sulfonamides from real aqueous samples. The proposed BMPM-based SPE combined with HPLC strategy showed low limit of detection ranged from 0.81 to 2.50 ng mL−1. The recoveries of sulfonamides at three spiked levels ranged from 90.2% to 105.5%, 80.9% to 104.7% and 81.0% to 104.5% for tap, lake and river water, respectively. The intra- and inter-day relative standard deviations (n = 5) were no more than 5.0% and 6.7%, respectively. These results indicated that the BMPM was very promising adsorbent for selective capture of other nitrogen-containing substances and the MPM could be performed functionalization by various affinity units.