Preparation Of Novel Magnetic Functional Materials And Their Application In Graphite Furnace Atomic Absorption Spectrometry

Graphite furnace atomic absorption spectrometry(GFAAS)has been widely used for the analysis of trace elements in environmental,food and biological samples due to the advantages of high sensitivity,low cost,easy operation and low consumption of sample.However,it is still faced with some difficulties in real sample analysis:the measured signals of GFAAS are susceptible to complicated sample matrix;the concentration of target element in real samples might be too low to be analyzed directly;different species of the same element cannot be distinguished.Thus,an appropriate sample pretreatment technique prior to GFAAS detection is often required to separate sample matrix and preconcentrate target analytes.Magnetic solid phase extraction(MSPE)is a novel sample pretreatment technology based on magnetic solid adsorbents.Compared with traditional solid-phase extraction techniques,MSPE possesses the advantages of simple operation,rapid phase separation,fast extraction dynamics and high enrichment factor.In MSPE,the magnetic adsorbents play a key role,which determines the selectivity and extraction kinetics.Therefore,it is of great significance to develop new MSPE materials with fast adsorption/desorption kinetics and high selectivity.Some promising novel functional materials,such as porous organic polymer(POPs),imprinted materials and mesoporous silica can be introduced into magnetic adsorbents through appropriate synthetic methods or strategies.The obtained novel magnetic functional materials would inherit the advantages of easy magnetic separation,high porosity,good selectivity and size exclusion property,which is benefit for the improvement of extraction kinetic and selectivity of MSPE based methodologies.The aim of this dissertation is to explore and prepare novel magnetic functional materials with abundant adsorption sites,good selectivity and fast extraction kinetic,including magnetic POPs with rich functional groups and magnetic imprinted materials based on different substrates or imprinting strategy;to develop new methods of MSPE coupled with GFAAS detection for the analysis of trace element and their species in various real samples.The major contents of this dissertation are described as follows:(1)Magnetic porous organic polymers(TPAB-PAR-MPOPs)were successfully synthesized in aqueous solution through a simple diazo-coupling reaction.The prepared TPAB-PAR-MPOPs possessed the advantages of large surface area,high porosity,abundant functional groups and easy magnetic separation,and they exhibited high adsorption capacity and fast adsorption kinetic for Pb(?)and Hg(?).Then the prepared TPAB-PAR-MPOPs were employed as MSPE adsorbent and a new method of MSPE with GFAAS detection was developed for the analysis of trace Pb(?)and Hg(?)in environmental water samples.Under the optimized conditions,a high enrichment factor of 150-fold was obtained.The limits of detection(LODs)of the developed method were 0.009 and 0.017 ?g L-1 for Pb(?)and Hg(?)with relative standard deviations(RSDs)of 8.3 and 8.0%(n?7,CPb(?)=0.05 ?g L-1,CHg(?)=0.25 ?g L-1),respectively.The developed MSPE-GFAAS method has the advantages of rapid phase separation,high sensitivity,environmental friendly and is easy to achieve batch operation.Three large volume water samples including tap water,East Lake water and Yangtze river water were successfully analyzed by the developed method.(2)Magnetic high crosslinked polymers(PVIM-MNPs)were prepared through a simple emulsion polymerization reaction in aqueous solution.With the addition of mercaptosuccinic acid,which acted as a ligand exchanger,both of silver nanoparticles(AgNPs)and Ag ions(Ag+)were retained on the PVIM-MNPs in a wide pH range(4-8),and the sequential elution of Ag+ and AgNPs was easily achieved by using Na2S2O3 and HNO3,respectively.Based on it,a new approach coupling ligand assisted-MSPE with GFAAS detection was proposed for the speciation of Ag+ and AgNPs in environmental water samples.Under the optimized conditions,the LODs of the proposed method were 7.3 and 8.2 ng L-1 for Ag+ and AgNPs with RSDs of 6.4 and 7.0%(CAg=50 ng L-1,n=7),respectively.The proposed method is simple,fast,sensitive and easy to achieve batch operation,and it could be used for the quantification of Ag+ and various coating modified AgNPs with a size range of 5-120 nm.Finally,the ligand-assisted MSPE-GFAAS method was successfully applied to determine Ag+ and AgNPs in four water samples including tap water,East Lake water,Yangtze River water and spring water,which can be further used for evaluating the environmental impact of Ag+ and AgNPs.(3)Poly(1-vinylimidazole)functionalized gold ion imprinted polymer coated magnetic nanoparticles(MNPs@PVIM-Au-IIP)were prepared by surface imprinting technique.The prepared MNPs@PVIM-Au-IIP exhibited good selectivity,fast adsorption kinetic(5 min)and high adsorption capacity(185 mg g-1)toward Au(?).Based on it,a novel method of ion imprinted(?)-MSPE coupled with GFAAS detection was proposed.Under the optimized conditions,a high enrichment factor of 100-fold was obtained,and the LOD of the proposed method is 7.9 ng L-1 for Au(?)with RSD of 7.4%(CAu(?)=50 ng L-1,n=7).The proposed II-MSPE-GFAAS method successfully realized the effective combination of an elemental selective sample pretreatment technology with an elemental selective detector,and it has the advantages of simple operation,good selectivity and high sensitivity.Besides,it showed good tolerance toward common co-existing ions and was successfully applied in the analysis of trace Au(?)in complicated samples including ore,sediment,environmental water and human urine samples.(4)With the pre-synthesized magnetic mesoporous silica as the substrate material,a cadmium ion imprinted magnetic mesoporous silica(Cd(?)-?-MMS)was prepared by surface imprinting technology combined with a simple sol-gel reaction.The prepared Cd(?)-?-MMS inherited the advantages of magnetic materials,mesoporous materials and ion imprinted materials,such as strong magnetism,uniform pore size,high surface area and abundant selective binding sites.Thus,a new method of ion imprinted(?)-MSPE coupled with GFAAS detection was proposed for the analysis of trace Cd(?)in complex matrix samples.The proposed method is sensitive,selective and easy to operate,and it was successfully applied for the determination of trace Cd(?)in East Lake water,Yangtze River water,human urine and rice samples.Besides,the proposed method exhibited a robust anti-interference ability due to the restricted access property of mesoporous channel and the specific recognition of ion imprinted sites toward Cd(?).It was used for direct analysis of Cd(?)in environmental water and diluted human urine samples without filtration step,demonstrating a good application potential for the analysis of trace Cd(?)in complex samples.(5)Based on the surface imprinting technique and double imprinting strategy,poly(4-vinylpyridine)functionalized double imprinted polymer coated magnetic nanoparticles(MNPs@DIP)were prepared with Pb(?)and 4 nm ZnO nanoparticles(NPs)employed as double templates.As sacrifice templates of ZnO-NPs left abundant transfer pores and adsorption sites in the imprinted coating after template removal steps,the prepared MNPs@DIP exhibited good selectivity,fast adsorption kinetic(7 min)and high adsorption capacity(150 mg g-1)toward Pb(?).Based on it,a new method of double imprinted(DI)-MSPE with GFAAS detection was established for the analysis of trace Pb(?)in environmental and biological sample.Under the optimal conditions,the LOD of the proposed method was 9.4 ng L-1 for Pb(?)with RSD of 6.9%(Cpb(?)=50 ng L-1,n=7).The proposed method was successfully applied for the fast,sensitive and selective analysis of trace Pb(?)in East Lake water,Yangtze River water,human urine and human hair samples.(6)By using cis-diamminedichloropalladium(?)as the dummy template of cisplatin(DDP),a magnetic molecular imprinted polymer material(MMIP)was prepared by surface imprinting technique combined with a sol-gel reaction.The prepared MMIP possess the advantages of easy to synthesis,no leakage of target molecules and good selectivity toward hydrate cisplatin other than intact cisplatin.After precipitation with AgNO3,intact cisplatin was transformed into hydrated cisplatin,which was then extracted by the prepared MMIP.Based on it,a new method of molecular imprinted(MI)-MSPE coupled with GFAAS detection was proposed for the analysis of trace free cisplatin in environmental and biological sample.The proposed method can achieve the selective separation and preconcentration of free cisplatin species without the requirement of chromatographic separation or derivative methods.It was successfully applied for the analysis of free cisplatin in East Lake water,hospital waste water and urine from cancer patients.