| The analysis and detection of basic compounds, which play a very significant part of chemicals with pharmaceutical and biological products, are of great value. By far the solid-phase extraction (SPE) combined with high performance liquid chromatography (HPLC) method are widely used for their separation and analysis. However, some problems in this method are difficult to solve. On the one hand, since the majority of the packing material is silica, which is fit for a narrow pH range (pH 2-8), in this pH range most basic compounds have the positive charge. And this makes them interact undesirably with the surface of silica-based reversed-phase materials because of the residual silanols, giving rise to irreversible adsorption, low recovery, tailing peaks in chromatography and poor reproducibility. On the other hand, the operation of solid-phase extraction is too complicated to achieve rapid, high-throughput results, and the packing materials are not easily recycled.To resolve these problems, the preparation of monodisperse macroporous crosslinked polymer microspheres using the seeded swelling polymerization method and application for the HPLC separation of basic compounds were studied systematically in this paper. Through the magnetic functionalization and surface modification of these microspheres, magnetic SPE packings were prepared, and applied for the rapid separation of basic compounds in complex samples.Firstly, monodisperse polystyrene seed microspheres were prepared by dispersion polymerization. The influence of monomer and initiator concentration and solvent composition on the dispersion of seeds were discussed respectively. Then, the porous polymer microspheres were prepared by seeded swelling polymerization. The influence of concentration and types of crosslinking agent and monomers on the pore size of the microspheres were studied by environmental scanning electron microscope (ESEM) systematically. These macroporous crosslinked polymer microspheres were applied to the chromatography packing and evaluated through separation of small molecules of aromatic compounds and basic drugs (oxytetracycline).In order to increase the mechanical strength of this polymer chromatography packing, polymer-coated silicas were developed and evaluated by separation of small molecules of aromatic compounds successfully.Using the characteristics of macropores, the simple method to prepare magnetic polymer microspheres was developed. Sulfonic groups were produced on the surface of microspheres through sulfonation. Then, magnetic fluid nanoparticles, that were soluble in nitric acid, were deposited on the microspheres by ion exchange method. To protect the magnetic fluid in the pores, the monomer of methyl methacrylate was applied to surface coating, and the carboxyl groups on the surface were introduced by hydrochloric acid hydrolysis. The magnetic microspheres were superparamagnetic, and the amount of magnetic fluid deposition was up to 20%. There were little effect of size and magnetic response after the surface coating with carboxyl functional groups. The coating thickness was up to 150 nm and the carboxyl content was about 127.4μmol/g. As magnetic solid-phase extraction packing, the magnetic polymer microspheres were applied for the detection of trace oxytetracycline (OTC) in milk. The results of OTC recovery in milk showed that the recovery were between 80%-90% obviously, and achieved the national standard. Besides, the magnetic SPE process was simple and rapid, and the packing materials could be reused. These highlighted the advantages of magnetic solid-phase extraction.In summary, this paper expanded the development of polymer packing materials and magnetic solid-phase extraction, and made some basis for the separation and analysis of basic compounds.
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