| Because of its simplicity of preparation, well permeability and good biocompatibility, organic polymer monolith, as one of novel materials, has wide applications in many fields of analytical chemistry. By using monolith material, polymer monolith microextraction (PMME) can be coupled with high performance liquid chromatography (HPLC) in the mode of on-line or off-line. In on-line mode, samples could be introduced to instruments with minimal preparation and the preconcentration and clean-up steps are easily performed. Additionally, the on-line mode shows less matrix interference, better reproducibility and higher sensitivity than the off-line mode. Based on this background, we did several researches:for a manual injection HPLC system, an on-line equipment coupling PMME with HPLC was constructed; a novel organic polymer monolith was synthesized and optimized, its extraction performance was examined as well; a PMME-HPLC method for the determination of four priority pollutant chlorophenols from environmental and biological samples was established.1. Construction of an on-line system coupling PMME with manual injection HPLCBased on a manual injection HPLC, a facile equipment on-line coupling PMME with HPLC was constructed by using a home-made needle adapter. There are four states (equilibrium, extraction, desorption and analysis) existing in the manipulation of such an equipment to accomplish the function of on-line extraction and HPLC analysis. Meanwhile, during the investigation, we found that a longer time for sample extraction could sufficiently avoid the impact of dead volume of system; a higher flow rate (up to0.4mL/min) could be tolerated by the needle adapter without any leakage; a back-flush desorption at a low flow rate and a separation at a high flow rate could attain a good separation and solve the problems of peak broadening and tailing, by making the analytes be desorbed in on a narrow band and retained at head of separation column before separation. Under the optimized condition,5μg/mL pentachlorophenol solutions were analyzed. Results showed that a good extraction efficiency was performed and the relative standard deviations (RSDs) of retention time and peak area were below2.5%, which indicated great potential for further application.2. A PMME-HPLC method established for the determination of chlorophenols from environmental and biological samplesA PMME-HPLC method was established for the determination of2-chlorophenol,2,4-dichlorophenol,2,4,6-trichlorophenol and pentachlorophenol listed in EPA priority pollutants from lake water, tap water and serum samples, by using poly(4-vinylpyridine-co-ethylene glycol dimethacrylate)[poly(VP-co-EGDMA)] monolith. The effect of the dosage of porogen polyethylene glycol6000(PEG) on back pressure and extraction performance of the monolith was investigated, and results showed that the best extraction performance was achieved when the amount of PEG added in the prepolymerization solution was70mg. Moreover, the optimal PMME condition was obtained at the flow rate of0.4mL/min for extraction,5min for extraction and desorption and the sample pH at5. Under the optimized PMME condition, four priority chlorophenols were determined with limits of detection in the range of0.3-1.4ng/mL, extraction efficiencies in the range of80.6%-91.7%, recoveries in the range of94.7%-106%and76.8%-86.3%for water arid serum, respectively, and the intra-and inter-day precision with RSDs of less than7.9%. Results mentioned above showed that the established PMME-HPLC method could be used in the extraction and determination of these four chlorophenols from environmental and biological samples. |
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