Study Of Sample Pretreatment And Microfluidic Chip And Its Application On Water Treatment And Water Environment Analysis

Along with the progress of science and technology,high-speed development of industrialization and urbanization,the living environment of human society is facing increasingly serious threats,the problem of environmental pollution have become increasingly prominent,the ecological environment has been an unprecedented vandalism.Therefore,the analysis and monitoring of harmful substances in the environment is very important and necessary in the field of environmental science.Water environment is one of the basic elements of the environment,it is the important place to live and product for human being,and it is also the most serious areas of human impact and destruction.The pollution and destruction of water environment have become one of the main environmental problems in the world.The water environment science research,especially the analysis of the water environment pollution has attracted much attention.Because of the current municipal wastewater treatment plants can not completely remove the organic pollutants and inorganic pollutants.It will cause a serious impact on human health and the ecological environment when these pollutants come into the environment along with effluent and sludge.Therefore,it is of great practical significance to study the content of these pollutants in wastewater treatment plants and their migration and transformation.It is difficult to direct determination of the analytes due to the low concentration,complex composition and serious interference substances in the real sewage and sludge samples.Thus,it is necessary to carry out appropriate sample pretreatment to isolate and enrich the target analytes to improve the accuracy of the analytical method and the detection limit.To solve some problems in the environmental analysis,such as the use of conventional instruments can not realize direct detection of trace or ultra trace pollutants in water environment,large reagent consumption,high cost,matrix interference,the laboratory instrument can not realise online detection,we developed the main research contents as follows:(1)liquid–liquid microextraction followed by high-performance liquid chromatography with UV detection was applied to determine Isocarbophos,Parathion-methyl,Triazophos,Phoxim,and Chlorpyrifos-methyl in water samples.1-Bromobutane was used as the extraction solvent,which has a higher density than water and low toxicity.Centrifugation and disperser solvent were not required in this microextraction procedure.Under the optimum conditions,enrichment factors ranging from 196 to 237 and limits of detection below 0.38 μg/L were obtained for the determination of target pesticides in water.Good linearities(r >0.9992)were obtained within the range of 1–500 μg/L for all the compounds.The relative standard deviations were in the range of 1.62%–2.86% and the recoveries of spiked samples ranged from 85.40 to 101.07%.The whole proposed methodology is simple,rapid,sensitive and environmentally friendly for determining traces of organophosphorus pesticides in the water samples.(2)A novel dispersive solid-phase microextraction combined with vortex-assisted dispersive liquid-liquid microextraction based on solidification of floating organic droplet was developed for the determination of eight benzoylurea insecticides in sewage sludge samples before high-performance liquid chromatography with ultraviolet detection.First,the organic components in activated sludge were extracted by acetone,and clean-up of the extract was conducted by dispersive solid-phase extraction using modified activated carbon as the sorbent,and then the target was enriched by vortex-assisted dispersive liquid–liquid microextraction based on solidification of floating organic droplet.This method can not only eliminate the interference compounds such as organic pigment,fatty acid,protein,fat and other impurities from the activated sludge,and it can also be exploited for effective separation and preconcentration of the targer analyte at low concentration levels before the detection.Under the optimum conditions,the linearity of the method was in the range 2–500 ng/g with correlation coefficients(r)of 0.9993-0.9999.The limits of detection were in the range of 0.08-0.56 ng/g.The relative standard deviations varied from 2.16 to 6.26%(n = 5).The enrichment factors ranged from 104 to 118.The extraction recoveries ranged from 81.05 to 97.82% for all of the analytes.The good performance has demonstrated that the proposed methodology has a strong potential application value for the analysis and detection of trace pollutants in the complex matrices.(3)In present study,a convenient,sensitive,rapid and simple method was developed on microfluidic chip which was integrated with on-line complexing and laser-induced fluorescence detection.A rhodamine derivative(RD)was developed as a fluorescent chemosensor for Hg(II).It exhibited high selective recognition toward Hg(II)over other examined metal ions in water samples.Under the optimized conditions,the response was linearly proportional to the concentration of Hg(II)in the range of 0–70 μM with a detection limit of 0.026 μM.Satisfactory repeatability and reproducibility was achieved,with relative standard deviations(RSD)of 6.62%.Finally,the established method was also successfully applied for the determination of Hg(II)in real water samples.Recoveries obtained for the determination of Hg(II)in spiking samples ranged from 86.60% to 94.37%.(4)A rapid and simple method using magnetic multi-walled carbon nanotubes(MWCNTS),as a solid-phase extraction(SPE)sorbent,has been successfully developed for extraction and preconcentration trace amounts of Cr(III)in water samples has been established.The synthesized magnetic-MWCNTs nanocomposite was characterized by scanning electron microscopy(SEM),transmission electron microscopy(TEM),Fourier transform infrared spectroscopy(FT-IR),X-ray photoelectron spectroscopy(XPS)and X-ray diffraction(XRD).A rhodamine derivative(R1)was synthesized and characterized as a highly selective and sensitive fluorescent derivatizing agent for Cr(III).After SPE procedure,the Cr(III)analysis was performed by flow injection microfluidic chip with on-line fluorescent derivatization and laser-induced fluorescence(LIF)spectroscopy detection.The parameters,which affected the efficiency of the developed method were investigated and optimized.Under the optimized conditions,the method exhibited a linear dynamic range of 0–10.0 nM with a detection limit of 0.094 nM and an enrichment factor of 38.Furthermore,speciation of chromium in real wastewater samples from the urban sewage treatment plants were analyzed and good recoveries were obtained from 87.67 to 104.00%.The proposed method has the potential to develop the inexpensive,portable on-line monitoring of micro spectrometers.