Preparation Of Dummy-template-based Molecularly Imprinted Polymers And Its Application In Analysis Of Phthalate Esters

In recent years,phthalate esters(PAEs)have attracted more and more attention of scholars and the public because of their ubiquity and harmfulness.PAEs are almost insoluble in water and usually appear to be the trace level.Therefore,it is necessary to prepare a high-efficient separation and enrichment material as well as develop a sensitive and accurate detection method to satisfy the analysis of PAEs.In this paper,a type of molecularly imprinted polymer(MIP)material adopting dummy-template imprinting technology was prepared,which possessd selective adsorption performance for six phthalates categorized as environmental priority pollutants,including dimethyl phthalate(DMP),diethyl phthalate(DEP),dibutyl phthalate(DBP),butyl benzyl phthalate(BBP),bis(2-ethylhexyl)phthalate(DEHP)and Di-n-octyl phthalate(DNOP).What's more,the adsorption property of the MIP towards six phthalates was also studied.Finally,a sort of analytic method(magnetic solid phase extraction-dispersion liquid-liquid microextracti on-gas chromatography-mass spectrometry)to the determination of trace PAEs was proposed that was successfully applied to the analysis of real waters.The main research contents included the follows:(1)A kind of novel molecularly imprinted polymers(MIP s)adopting sol-gel surfacial molecular imprinting technique was synthesized by using magnetic graphene oxide-mesoporous silica(MGO@mSiO2)as a carrier,dipropyl phthalate(DPRP)and diisononyl phthalate(DINP)as virtual templates,phenyl trimethoxide oxysilane(PTMOS)and 3-aminopropyltriethoxysilane(APTES)as functional monomers,and tetraethyl orthosilicate(TEOS)as a cross-linking agent.At the same time,the non-imprinted polymers(NIPs)were prepared as the same way as MIPs except having no templates.The synthesized materials were characterized by means of scanning electron microscopy(SEM),transmission electron microscopy(TEM),Fourier transform infrared spectroscopy(FT-IR),X-ray diffraction(XRD),thermogravimetric analysis(TGA),nitrogen adsorption-desorption machine and magnetic performance analysis(VSM).(2)The adsorption performances of MIPs were evaluated by adsorption isotherms,kinetics and adsorption selectivity experiments.The results showed that the optimal pH of the solution was 7.0,and the adsorption capacity gradually increased with the rise of temperature or initial concentration.Besides,the adsorption kinetics followed pseudo-second-order kinetics model with the adsorption equilibrium time of about 120 min and the equilibrium adsorption capacity of 2.3-4.8 mg g-1 for individual PAEs at 298 K.The curve fittings of adsorption isotherm were in accordance with the Freundlich model,which meant that the adsorption sites were heterogeneous and multi-layered,and the adsorption procedure was endothermic and spontaneous.The imprinted factor was up to 3.89,and the MIPs could be reused 6 times without significant losses.(3)An original detection method(magnetic solid phase extraction-dispersion liquid-liquid microextraction-gas chromatography-mass spectrometry,MIPs-SPE-DLLME-GC/MS)employing the synthesized MIPs as the solid phase extraction adsorbent was proposed.The influenced factors on SPE(including pH,extraction time,eluent type,eluent volume,elution time and solution volume)and on DLLME(including extractant type,extractant volume and salt effect)were explored,and the best SPE-DLLME conditions were acquired.The analytical performance of MIPs-SPE-DLLME-GC/MS was investigated.The outcomes showed that the enrichment facors of DMP,DEP,DBP,BBP,DEHP and NDOP were 1158?1253?1549?1039?1064 and 2666,the limits of detection(LODs)were 0.05?0.025?0.025?0.015?0.01?0.05 ?g L-1,and the limits of quantity(LOQs)were 0.2?0.1?0.1?0.05?0.05?0.2 ?g L-1.This method was also applied to the analysis and detection of PAEs in river,lake,well and pond water samples,the calculated standard recoveries were between 91.0%-121.0%and the RSD was in the range of 0.53%to 4.48%.It can be found that the MIPs-SPE-DLLME-GC/MS method possesses many prosperous advantages,such as high enrichment factor,low limit of detection,high accuracy,convenient operation,excellent reproducibility and economical property,and can be suitable for separation and detection of trace PAEs in actual water samples.