| There is the potential risk of trace analytes in environmental,food and biological samples to humans,animals and even the ecosystems.As a result,the analysis of trace analyses in complex matrices is becoming more and more important.Although the tremendous evolution of the analytical instrument that has occurred in recent decades,the analysis of complex sample with low concentration analytes still cannot achieve the desired results.Sample preparation is an important procedure in analytical workflow,which can separate trace analyses from complex matrices avoiding interferences and can concentrate them increasing detection sensitivity.As a result,it has been widely applied in proteomics and peptidomics analysis,environmental monitoring and disease diagnosis,which is not only playing an important role.but traditional sample preparation is time consuming,is prone to introducing contamination and is more difficult to automate than other steps,which also facing more serious challenges.Solid-phase extraction(SPE)as a classic sample preparation technology has recently drawn a great deal of attention and has developed a series of novel SPE methods.They overcome the drawbacks of classic SPE,such as time consuming,labor intensive,relatively expensive especially for large volume.Magnetic SPE(MSPE),a novel mode of SPE based on magnetic or magnetizable adsorbents,has become the focus on analytical chemistry.In MSPE procedure,the magnetic adsorbents are usually dispersed into the sample solution directly.The targeted analytes are adsorbed onto the magnetic adsorbents,and then separated from the sample solution using an external magnetic field directly.Compared with conventional SPE techniques,MSPE avoids filtration or centrifugation by employing magnetic separation.MSPE obviously enhances the extraction efficiency and simplies the pretreatment procedure,providing another way for separation science,which is a promising technique for sample preparation.Magnetic sorbents is a crucial factor to efficiency of the MSPE.Recently,various new nanomaterials,such as graphene(G),carbon nanotubes(CNTs)and metal organic framework material(MOFs),provides a broad space for MSPE technology.The application of magnetic materials as MSPE adsorbents has received considerable attention mainly due to its convenience and compatibility.Functionalized magnetic materials offer greater extraction capacity and better selectivity.Therefore,the research of novel magnetic materials plays an important role to build faster and more sensitive methods for MSPE.This paper is devoted to studies on the synthesis and application of MSPE magnetic carbon materials.Three magnetic carbon materials synthesized by different means were used to develop high sensitive MSPE methods combining with high performance liquid chromatography(HPLC)These new method have been successfully applied to investigate environmental water samples.The main contents are shown below:1.Magnetic carbon nanotubes(Fe3O4@CNTs)was synthesized via the pyrolysis of ferrocene at high temperatures,in which Fe3O4 was encapsulated in CNTs.Scanning electron microscope(SEM),transmission electron microscope(TEM),X-ray powder diffraction(XRD)and magnetic measurement demonstrated that Fe3O4@CNTs has been prepared successfully.The extraction performance of Fe3O4@CNTs as a sorbent was evaluated by using four fluoroquinolones(FQs),ofloxacin(OFL),ciprofloxacin(CIP),lomefloxacin hydrochloride(LOM)and enrofloxacin(ENR)as a model analytes.Under the optimum conditions,detection limits of the four analytes were 0.2、0.5、0.2、0.2μg/L,respectively,which were obtained by UV detection.This developed method has been successfully applied for the detection of FQs in environmental water samples by using MSPE-HPLC.And the recoveries of the four FQs spiked in real water samples were in the range of 84.0～114.6%with relative standard deviations ranging from 1.2-5.0%.2.Magnetic graphene composites(Fe3O4@PDA-G)has been prepared for(MSPE)of organophosphorus(OPPs).Polydopamine(PDA)spontaneously aggregated on Fe3O4 forming Fe3O4@PDA with core-shell structure,and then Fe3O4@PDA was bonded to graphene modified with thiol-group based on Michael addition/Schiff base reactions.Owing to PDA’s unique properties such as abundant π electron and excellent dispersibility in water and extraordinary biocompatibility,PDA not only as a protective layer of Fe3O4,is able to provide analysis of adsorption sites,while also improving the hydrophilicity of graphene.Fe3O4@PDA-G has been successfully synthesized,which were confirmed by TEM,XRD,thermal gravimetric analysis(TGA)and raman spectrum and so on.It was applied to enrich three OPPs,parathion-methyl(Methyl),phentriazophos(Tria)and parathion(Para),and detected by HPLC after eluting via methanol.We investigated the conditions of enrichment and isolation.Under optimal experimental conditions,both detection limits of them were 0.2μg/L,average recoveries and relative standard deviation were in range of 89.0-1 14.7%and 1.2-5.8%respectively.3.A porous Co@C magnetic composite has been synthesized using cobalt nitrate,lithium hydroxide,benzene and imidazole as raw materials by solid phase reaction,and then removing the lithium hydroxide via acetic acid.Co@C magnetic composite was applied as an absorbent for extracting organophosphorus from environmental water samples.The as-prepared Co@C was characterized by SEM,TEM,XRD and TGA and so on,proving that the carbon content of the material was about 8.42%and that had excellent magnetic response.It was applied to enrich three OPPs,parathion-methyl(Methyl),phentriazophos(Tria)and parathion(Para),and detected by HPLC-UV.We investigated the conditions of enrichment and isolation.Under optimal experimental conditions,detection limits of Methyl,Tria and Para were 0.4μg/L,0.05μg/L and 0.3μg/L.Average recoveries and relative standard deviation were in range of 80.2-108.4%and 1.0-4.7%respectively. |
