Graphene Oxide Grafted Silica Monolith For The Determination Of Polycyclic Aromatic Hydrocarbons

Graphene(G)is a novel two-dimensional honeycomb structure carbon nanomaterial with large specific surface area and strong mechanical properties.Graphene Oxide(GO)is a derivative of graphene,which can be obtained by oxidation and stripping of graphite.GO has similar structural features to G,but only adds abundant carboxyl and hydroxyl groups to the surface of the sheet,which has good water dispersibility and is easily modified in various covalent or non-covalent manners to various separation materials or carriers to obtain a material having high-quality extraction properties,it has good application prospects in separation science fields such as sample pretreatment.The silica monolith is a commonly used extraction medium with a continuous porous structure,good permeability,and easy modification.Grafting GO onto the surface of the silica monolith is beneficial to improve the selectivity,separation and enrichment performance of the monolith.Polycyclic aromatic hydrocarbons(PAHs)are widely found in the environment and are carcinogenic,teratogenic,mutagenic,low in sample content,complex in matrix,and require effective pretreatment before detection.In this paper,GO was grafted onto the surface of a self-made aminated silica monolith by amidation reaction to prepare a GO grafted silica monolith.As a solid phase micro-extraction medium,combined with high performance liquid chromatography-ultraviolet detection(HPLC-UV),a simple,efficient and sensitive extraction method for PAHs was established and used for the detection of real samples.The results were satisfactory.The experimental results are as follows:(1)GO was prepared by the improved Hummers method,and the prepared GO was characterized by means of Fourier transform infrared and Raman spectroscopy.The results show that the prepared GO has a high degree of oxidation and is rich in functional groups such as carboxyl groups.(2)The silica monolith was prepared by in-situ polymerization of TMOS by sol-gel method,and then amino group was introduced by APTMS,the GO grafted silica monolith was prepared by grafting GO onto the surface of the monolith throw amidation reaction.The monolith prepared by the pretreated capillary has no phenomena such as detachment and fault.After the experiment was optimized,the amount of each substance was determined as:0.90mL TMOS,0.10 g PEG,0.22 g Urea,2 mL,0.01 mol/L HAc,1 mL APTMS.The optimum grafting conditions of GO were:1 mL,0.02 mg/mL GO water dispersion,and reaction at 40?for 6 h.The newly prepared GO grafted silica monolith was characterized by Scanning electron microscopy,Elemental analysis and Raman spectroscopy.The silica monolith has good permeability and GO has a high bonding amount.(3)The GO grafted silica monolith was used as the extraction medium,and combined with HPLC-UV detection,the extraction and enrichment performance for typical PAHs Pyr,BaP and DahA were investigated.Under the optimized conditions,the enrichment factors of Pyr,BaP and DahA were 78.5,98.2 and 102.4 respectively,and the extraction capacities were0.15?g,0.22?g,and 0.26?g respectively.The?-?stacking interaction and hydrophobic interaction between GO and PAHs make the monolith show strong enrichment ability for typical PAHs.A quantitative analysis method for 9 kinds of PAHs Pyr,BaA,Chr,BbF,BkF,BaP,DahA,BghiA,InP were set up,the detection limit of the method is 0.02-0.11?g/L(LOD,S/N=3),the limit of quantification is 0.07-0.36?g/L(LOQ,S/N=10),the PAHs have a good linear relationship in the range of 0.1-150?g/L(R~2?0.9946).The GO grafted silica monolith has excellent enrichment and separation effects.(4)The PAHs content of 20 real samples(cigarette smoke,wastewater and atmospheric particulate matter)was detected by the newly method.The recoveries of PAHs at 3 different concentrations in the real samples were 81.5%-107.8%,and the relative standard deviation(RSD)were 1.0%-6.5%(n=3).The newly prepared GO grafted silica monolith exhibits high extraction and enrichment ability for typical PAHs.The established detection method is accurate,sensitive,simple and reliable,provides a new way for the detection of low-content real sample PAHs.