| Solid-phase microextraction（SPME）has become an important sample pretreatment technology because of its excellent extraction performance,simple preparation method,quick operation procedure.As a branch of SPME,monolithic column microextraction（MCM）have many advantages,such as simple operation,short time consuming,high efficiency,good reproducibility,fast analysis speed,low consumption of organic solvents and so on,it is suitable for the enrichment of trace or ultra-trace samples,and it is easy to realize automatic operation while improving the analysis precision,which is conform to the trend of sample pretreatment technology towards environmental friendly,miniaturization,and automation.Monolithic column is a kind of uniform and stable rod-like whole formed by in-situ polymerization of reaction monomers,crosslinking agents and pore-forming agents in tubular materials such as capillary or chromatographic column under certain conditions,so it is also called rod-like column,continuous bed and so on.Compared with extraction fiber and coated capillary extraction column,capillary monolithic column increases the total amount of extraction materials,thus significantly improving the extraction capacity;compared with packed column,monolithic column not only does not need to be packed with materials,but also its special through holes provide a larger channel for the liquid to flow through,and the slow diffusion mass transfer is replaced by faster countercurrent mass transfer,which is beneficial to improving extraction efficiency and is of great significance in the field of sample pretreatment.In this paper,two kinds of organic polymer monolithic columns and one organic-inorganic hybrid monolithic column were prepared,and three kinds of capillary monolithic columns were used as extraction media for MCM.The extraction properties of trace four chlorophenols,six kinds of organic pesticides and seven kinds of polycyclic aromatic hydrocarbons in environmental samples were studied respectively.The research contents of this paper are as follows:Chapter 1:The classification of monolithic column（inorganic silica gel monolithic column,organic polymerization monolithic column and organic-inorganic hybrid monolithic column）,preparation methods（organic polymerization,doping,post-modification and 3D printing method,etc.）and applications in sample pretreatment fields（environmental detection,biological detection,food safety and medical and health care）were reviewed in detail.Chapter 2:Benzene-1,3,5-tricarbohydrazide was synthesized from trimethyl-1,3,5-trimellitate and hydrazine hydrate under relatively mild conditions（80℃,12 h）,and three kinds of organic polymerization with different nitrogen element contents were prepared with styrene,N,N’-methylene bisacrylamide and acryloyl chloride as crosslinking agents.The prepared benzene-1,3,5-tricarbohydrazide and three monolithic columns were characterized by 1H NMR,Fourier transform infrared spectroscopy and scanning electron microscopy.And the prepared monolithic column was used as the extraction medium of capillary monolithic column microextraction to explore its extraction performance for chlorophenol.It was found that the monolithic column with more nitrogen element content has better adsorption capacity for chlorophenol pollutants.The orthogonal experiment was used to optimize the affecting factors of the extraction.Under the optimal conditions,four kinds of chlorophenol pollutants were captured and analyzed by HPLC.Chapter 3:1,5-bis（hexa-5-ene-1-oxy）naphthalene with rich benzene ring structure was prepared from 1,5-dihydroxy naphthalene and 6-bromo-1-hexene by the reaction between hydroxyl and bromine atoms,and it was characterized by 1HNMR and Fourier transform infrared spectroscopy.Using the prepared 1,5-bis（hex-5-ene-1-oxy）naphthalene as functional monomer,glycidyl methacrylate and ethylene glycol dimethacrylate as crosslinking agents,the 1,5-bis（hex-5-ene-1-oxy）naphthalene hybrid monolithic column was prepared under the conditions of azodiisobutyronitrile initiation and heating.The existence of functional monomers introduces a large number of benzene rings into the monolithic column,which made the prepared monolithic column showed good extraction performance for organic pesticides with rich benzene ring structure.Under the optimum extraction conditions,the linear range was 0.34-1000μg·L-1,the relative standard deviation was less than 4.58%,the LOD value was 0.02-0.89μg·L-1,and the LOQ value was 0.07-2.96μg·L-1.Chapter 4:Carboxylated multi-walled carbon nanotubes were doped into the organic-inorganic hybrid monolithic column prepared by using 3-aminopropyl triethoxysilane and tetraethyl orthosilicate as crosslinking agents,thus increasing the binding sites between the prepared monolithic column and the target adsorbate（polycyclic aromatic hydrocarbons）and improving its adsorption performance.Fourier transform infrared spectroscopy,scanning electron microscope and nitrogen adsorption-desorption isotherm were used to characterize the monolithic column.After optimizing the conditions affecting the extraction effect,polycyclic aromatic hydrocarbons in actual water samples were extracted with this monolithic column and detected by high performance liquid chromatography.The results showed that the monolithic column rich in delocalizedπbond structure has excellent enrichment performance for polycyclic aromatic hydrocarbons,the linear correlation coefficient was greater than 0.9932,the low detection limit was 0.04-1.17μg·L-1,the low quantitative limit was 0.13-3.91μg·L-1,and the relative standard deviation was less than 4.76%,which indicated that this method has good linearity,wide linear range and good repeatability. |
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