| Due to the complexity of real samples matrix and trace concentration level of analytes,it is essential to purify and enrich the analytes from environmental samples before the instrumental analysis.Trimethyl phosphate(TMP)is a new type of pollutant,having been detected in environmental samples.Because of its high polarity and volatility,few satisfying recoveries of TMP from conventional methods are obtained.In this study,to solve the problem,TMP molecularly imprinted polymer monolithic fiber(TMP-MEP-MF)was synthesized to be used as extraction materials of solid phase microextraction(SPME)by in-situ polymerization in fused silica capillary.Given that the high volatility of TMP and the complexity of real samples matrix,the method of headspace solid phase microextraction(HS-SPME)based on TMP-MIP-MF,coupled with GC-NPD and GC-MS,was established and compared with direct immersion solid phase microextraction(DI-SPME)and:in-tube molecularly imprinted polymer monolithic solid phase microextraction(In-tube MIPMME).It was proved that the method with the advantages of low limit of detection,good reproducibility and high recoveries had been successfully employed to the detection of TMP in real environmental water samples.The detailed research contents were listed as follows:1.The preparation and characterization of TMP molecularly imprinted polymer monolithic fiber:A novel TMP-MIP monolithic fiber was fabricated based on simple in-situ polymerization method,and then the fiber was characterized by fourier transform infrared spectroscope(FT-IR),scanning electron microscope(SEM),N2 adsorption-desorption isotherm and thermo gravimetric analysis(TGA).The results indicated that the MIP fiber was successfully prepared.Moreover,the MIP fiber possessed porous structure and large surface area(389.53 m2·g-1).Stability tests indicated that the materials had a good thermal stability and chemical stability,which were beneficial for the subsequent application.2.The establishment and evaluation of the analytical method of TMP-MIP monolithic fiber HS-SPME coupled with HS-SPME and GC-NPD:The TMP-MIP monolithic fiber was employed for the extraction of TMP.The extraction mode of HS-SPME was selected by comparing with DI-SPME and in-tube MIPMME.Also,the selectivity of the MIP fiber was studied by the extraction of five organophosphates.The results shown that selectivity of the fiber was good.Besides,the MIP fiber was compared with non-imprinted polymer(NIP)and commercial fibers(PDMS,PA)in extraction efficiency,which indicated that the MIP monolithic fiber had best extraction efficiency.After that,the headspace adsorption kinetic performances of TMP molecularly imprinted monolithic fiber were investigated with the pseudo-first order kinetic model and pseudo-second order kinetic model.The results indicated that the adsorption performance fitted pseudo-first-order kinetic model well,and the adsorption reached equilibrium at about 60 min.The Langmuir model,Bi-Langmuir model and Freundlich model were used to fit the adsorption isotherm.The fitting results of adsorption isotherm indicated that experimental data fitted Bi-Langmuir model the best,which meant that the binding between MIP monolithic fiber and TMP had two types of recognition sites.Subsequently,the analytical method of MIP monolithic fiber HS-SPME coupled with GC-NPD was established and evaluated under the optimum conditions.Finally,the analytical method was applied for the extraction of TMP in couples of real water samples.The method shown a good linear relationship in the range of 0.02-50 μg·L-1(R>0.999),and the limit of detection(LOD),based on signal-to-noise ratio(S/N)of 3,was 0.00036 μg·L-1.The MIP fiber was employed for the concentration of TMP in seven water samples with good added recoveries from 88.7%to 103.2%.The proposed method with the advantages of good recoveries,low limit of detection,simplicity and low cost,could be applied to the quantitative analysis of TMP in real environmental water samples. |
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