Preparation And Performance Exploration Of Novel Solid-phase Microextraction Fibers Based On Porous Carbons

Sample preparation is a very important step for sample analysis.However,due to the time-consuming and large amount of organic solvents consumed by traditional sample pretreatment methods,new sample pretreatment methods such as solid-phase microextraction?SPME?have been widely used in sample analysis.SPME is a new type of sample pretreatment technology which integrates sampling,extraction,enrichment and injection.SPME is almost solvent-less,and the operation process is simple,which effectively solves the shortcomings of traditional sample pretreatment methods.The coatings are the core part of SPME technology,but the commercial fiber coatings are difficult to meet the analysis needs due to the limited types and poor specificity.Therefore,the development of new SPME coating materials is an important direction of SPME development.Because of its excellent chemical,mechanical and thermal stability,carbon based materials have been used as coatings materials in SPME.The main work of this paper is to prepare novel fibers based on graphene and biomass derived carbon.Combined with the corresponding detection methods,two kinds of organic pollutants as the organophosphorus pesticides?OPPs?and polycyclic aromatic hydrocarbons?PAHs?in the water environment were detected.The main contents and conclusions of this paper are as follows:1. The SPME coating of hydroxyl-functionalized graphene?G-OH?modified by eighteen alkyl quaternary ammonium salt was prepared by sol-gel method for the first time.Based on the homemade fiber,the headspace-solid phase microextraction-gas chromatography-flame photometric detector?HS-SPME-GC-FPD?method was established to evaluate the performance of the novel homemade fibers.The proposed method showed good linear relationship for the eight OPPs?R²?0.9957?in the range of concentrations,with the limit of quantification of 0.11mg L^-1-3.37mg L^-1,and the detection limit of 0.03mg L^-1-1.01mg L^-1.In addition,the analysis of aromatic amines in the fiber is relatively stable?RSDs<10%?,and the repeatability of the fiber preparation method proposed in this work is within the acceptable range?RSDs?15.86%?.In addition,the fiber can be reused at least 150 times,and has good solvent resistance,which proves that the homemade fiber has successfully overcome the existing fatal disadvantages of commercial fiber,such as short life and solvent intolerance.Compared with the commercial polyacrylate?PA?fiber and other reported methods,the excellent extraction ability of the homemade fiber was verified.In addition,in order to further evaluate the ability of the homemade fiber to analyze pesticide residues in water samples,the homemade fiber was used for the multi residue analysis of OPPs in two real environmental water samples,and good recovery?90.36%-116.63%?and acceptable reproducibility?RSDs?12.57%?were obtained.Therefore,the proposed method based on the novel homemade fiber provides a new possibility for the analysis of the eight prohibited or restricted OPPs.The results also showed that the fibers had a longer lifetime?more than150 times?and good solvent resistance.2. Taking banana peel as precursor material and magnesium nitrate as template and activator,green biomass-derived carbon?Mg O-banana peel activated carbon,Mg O-BPAC?with obvious pore structure characteristics was synthesized.With the help of silicone sealant,Mg O-BPAC was fixed on the surface of stainless steel wire to prepare a new type of SPME fiber.In this work,the HS-SPME-GC-MS method based on Mg O-BPAC fiber was proposed by combining with gas chromatography-mass spectrometry?GC-MS?.The experimental results showed that Mg O-BPAC fiber has good extraction efficiency for the six polycyclic aromatic hydrocarbons?PAHs?.The analytical parameters of this method were investigated to confirm the effectiveness of the HS-SPME-GC-MS method for PAHs in water samples.A lower detection limit(0.86 ng L^-1-2.12 ng L^-1)was obtained,with satisfactory repeatability?RSDs?10.30%?and reproducibility?RSDs?13.92%?.In order to verify the working performance of the homemade fiber,the HS-SPME method based on Mg O-BPAC fiber was applied to the determination of the six PAHs in different real environmental water samples,and good recoveries?92.67%-14.45%?was obtained.This research proves that the introduction of biochar material as the functional component of the fiber coating in this work promotes the adsorption process of the target aromatic component of SPME,thus opening up a new method of combining biochar material and SPME.It is of great significance for the monitoring of persistent pollutants in the environment.