Preparation Of Mesoporous Carbon Nitride And Its Composites And Their Applications In Novel Sample Preparation Methods

Mesoporous carbon nitride?MCN?materials have popular applications in catalysis,sample preparation,biomedicine and many other fields due to the unique characteristics of tunable pore structure,excellent dispersion,large specific surface area,specific pore volume,active chemical sites,high chemical stability,non-toxicity and innocuity.In this paper,mesoporous carbon nitride and its composites were prepared and applied for the determination of target analytes in food,biological and environmental samples by column assisted-dispersive solid phase extraction-high performance liquid chromatography?CA-d SPE-HPLC?,solid phase microextraction gas chromatographic?SPME-GC?and ionic liquids assisted vaccum-headspace-solid phase microextraction-electrospray mass spectrometry?ILs-Vac-HSSPME-MS?method,respectively.The main contents are as follows:1.In this work,mesoporous graphitic carbon nitride?MCN?was facile synthesized,and was applied as highly effective sorbent for enrichment of sulfonamides?SAs?from environmental water and milk samples for the first time.To overcome the difficulty in collecting and separating sorbent from matrix,a novel column assisted dispersive solid-phase extraction?CA-d SPE?method was designed.The as-prepared MCN was well characterized and the effecting parameters on CA-d SPE extraction efficiency were profoundly investigated and optimized.Under the optimized conditions,the limits of detection?LODs?for the five SAs investigated in the developed CA-d SPE method were achieved at 5 to 20 pg/m L with HPLC technique.The satisfactory recoveries were obtained in the range of 90.1-110.5% and 82.3-102.7% for environmental water and milk samples with relative standard deviations?RSDs?of 0.5-3.8% and 1.1-4.4%,respectively.The experimental results implied that the developed CA-d SPE method with MCN as the sorbent is a simple,time saving,sensitive and reliable sample preparation technique and looks forward to being further exploited for other applications.2.In this work,intergrating the advantage of MCN and NiCO₂O₄,a novel MCN@NiCO₂O₄ nanocomposite was synthesized by hydrothermal method and used as a solid phase microextraction coating.The MCN@NiCO₂O₄ coating was used for simultaneous extraction of three polychlorinated biphenyls?PCBs?and six polycyclic aromatic hydrocarbons?PAHs?from human serum sample via headspace SPME?HS-SPME?coupled with gas chromatography-flame ionization detector?GC-FID?method.The method maximized the elimination of matrix interference and finally get excelent experiment results.The LODs can be as low as 0.9 pg/m L under the use of most common GC-FID detector.Compared with pure MCN and NiCO₂O₄,MCN@NiCO₂O₄ coating can achieve better enrichment effect,longer lifetime,higher recovery and lower experimental error,and has been successfully applied for the analysis of complex serum samples.The interaction between MCN@NiCO₂O₄ and the targets was also hypothesized and verified,which was ultimately attributed to ?-? interaction,hydrogen bonding,?-complexation and coordination interaction.3.In this work,a novel ILs-Vac-HSSPME method established main to minimizing or completely eliminating the use of organic solvents,reducing the time or the labor and expanding the range of analytes applicable to HS-SPME.The ILs-Vac-HSSPME method combined two steps into one,selected the green ionic liquids solvent to replace traditional organic solvents to extract analytes in samples and then directly as an assisted solvent to solid phase microextraction.Due to the outstanding thermal-stability of ionic liquids,the novel ILs-Vac-HSSPME method provide a possibility of HS-SPME for a wider range of compounds rather than only volatile compounds with common instruments.In order to verify the established ILs-Vac-HSSPME method,three different phase samples of solid?soil sample?,liquid?water sample?and gas?cigarette smoke sample?were selected for determination.And PCBs and PBDEs in soil samples were selected to verify the accuracy of ILs-Vac-HSSPME method.Under the optimized conditions,LODs in ILs-Vac-HSSPME method were achieved at 0.05-0.40 ng/L for PCBs and 0.10-0.40 ng/L for PBDEs with GC-FID technique.The experimental results implied that the novel ILs-Vac-HSSPME method is a green,effient,time-saving,sensitive and reliable sample preparation technique and looks forward to expanding the further applications in other fields.