The Application Of Nanomaterials In Sample Pretreatment Technology

Analysis of contaminants in environmental matrices has always been a challenging task,not only because of the complexity of the sample,but also because the target contaminants are present at trace levels.Proper sample pretreatment techniques not only ensure satisfactory sensitivity by concentrating the analytes to the detectable limits of the analytical instrument,but also improve the selectivity of the method by removing interfering substances that are not of interest in the original matrix.In addition,proper sample pretreatment can prevent potential damage to the analytical instrument.Therefore,finding a suitable sample preparation method is a permanent problem in the analysis of contaminants and residues in environmental and biological samples.1.A mechanochemical magnetic solid phase extraction(MCMSPE)method was developed for a one-pot extraction and enrichment of organoehlorine pesticides in tea leaves to demonstrate the advantage of using magnetic nanoparticles in the sample preparation process.The enriched analytes were subsequently detected by ultra-high performance liquid chromatography and gas chromatography mass spectrometry.The presence of magnetic metal-organic-framework(MMOF)(Fe3O4@MIL-100(Fe))nanoparticles help to rupture the cell walls in solid plant samples more thoroughly,and at the same time,act as a selective sorbent for the enrichment of target analytes.Compared to traditional methods,this approach signifieantly shortens the sample processing time from tens of minutes to tens of seconds.The parameters of the procedure were systematically studied and optimized to achieve good limits of detection(0.62 to 3.92 ng g-1,LOD S/N=3),significantly improved recoveries(81.46 to 113.59%),and good reproducibility(RSD 2.63-9.87%,n=5).The results indicated that this method can be applied for high throughput deternination of organoehlorine pesticides in tea leaves,and can be used for other dried plant samples.2.A sorbent-and-solvent co-enhanced direct mialysis in real-time mass spectrometry(SSE-DART-MS)method was established for high-throughput determination of trace pollutants in water.The use of sorbents to concentrate and solvents to assist the desorption ionization significantly enhanced the signals from the trace pollutants detected by DART-MS.Phthalic acid esters(PAEs)were used as model analytes to validate the SSE-DART-MS method.Graphitic carbon nitride(g-C3N4)-based materials with two morphologies and six organic solvents were employed to systematically evaluate the enhancements by the sorbent and solvent on DART-MS.A better analytical performance was achieved with the two-dimensional(2D)g-C3N4,than with three-dimensional(3D)g-C3N4/C,indicating that the morphologies of sorbents played a key role in DART-MS analysis.The MS signals of all the analytes were enhanced 10-100 times for the two materials in the presence of the solvents.With the SSE-DART-MS method,good limits of detection(LODs,S/N=3),in the range 0.05-0.5 ng/L,and good recovery,in the range 82.81-118.53%,were obtained for the PAEs.This study not only offers a reliable strategy for the coupling of solid phase extraction technique with DART-MS,but also presents valuable information for conducting other DART-MS analyses.3.A-?-CD-silica hybrid monolithic column was successfully prepared by sol-gel method based on ?-cyclodextrin(?-CD),and successfully applied to pipette tip solid phase extraction.This is a promising solid phase extraction technique.As a new type of solid phase extraction mode,the solid phase extraction column is less expensive in the pipette,less solvent and consumption of the sample,easier to operate,time efficient,and more general than the conventional solid phase extraction column.Strong and other advantages.These advantages make the SPE column a promising technique for preparing samples in pipettes.In addition,the A-?-CD-silica hybrid monolithic column can provide good separation resolution for UV-filters.After solid phase extraction at the tip of the pipette,the adsorption rates of the four UV-filters were almost 70-100%,and low concentrations of UV-filters were successfully detected by DART?MS.This work demonstrates the good adsorption performance of A-?-CD-silica hybrid monolithic column for UV-filters,and also provides an idea for the detection of pollutants in the environment.