Application Of Macroporous Graphite Carbon Nitride Solid Phase Extraction Adsorption Material In Food Analysis

With high specific surface area and abundant pore structure,mesoporous carbon materials are expected to be a promising pretreatment adsorbent for chromatographic separation.The introduction of heterogeneous elements in the carbon material,such as nitrogen,can further modulate the structure and the surface chemical properties of materials,and also have wider application.Herein,a template approach is applied to the synthesis of mesoporous graphite carbon nitride?mpg-C₃N₄?,which could selectively adsorb benzene ring compounds and been applied to food samples pretreatment because of their large specific surface area and similar graphene structure.Based on this idea,we developed fast and efficient methods for detection of polycyclic aromatic hydrocarbons?PAHs?in the edible oil and tetracycline antibiotic residues of food.The main contents are summarized as follows:1.The mpg-C₃N₄are synthesized at high temperature by using 12nm 40%silica gel aqueous solution as template and cyanamide as precursor.The mpg-C₃N₄were obtained after the removal of the silica template by HF and fully characterized by using transmission electron microscopy?TEM?,nitrogen adsorption and Fourier transform infrared spectroscopy?FT-IR?.2.In our study,a solid-phase extraction?SPE?method wihch using mpg-C₃N₄ as adsorbent for purification of 15 PAHs in the edible oil was developed.The etrahydrofur an was used as the elution solvent for solid phase extraction.The concentrations of PAHs in the edible oil extract weredeterminedbyhighperformanceliquid chromatography-Fluorescence detector?HPLC-FLD?.The maximum adsorption capacity of the mpg-C₃N₄ to 15 PAHs ranged from 208.25ng/mg to 1508.76 ng/mg.The limit of detection?LOD?and limit of quantification?LOQ?of the developed method for 15 PAHs were0.07-1.45?g/kg and 0.24-4.83?g/kg,respectively.The recoveries of the actual samples ranged from 76.8%to 106.2%,and the RSD of intra-day and inter-day analysis were 0.6%-6.9%and 1.3%-8.4%.3.SPE method using mpg-C₃N₄ as adsorbent for purification of four tetracycline antibiotics in pork,honey and milk was developed.The concentrations of four tetracycline antibiotics extract were determined by high performance liquid chromatography-mass spectrometry?HLPC-MS/MS?.The maximum adsorption capacity of mpg-C₃N₄ to four tetracycline antibiotics is 1400 ng/mg-2200 ng/mg.The mixed solvent of ethyl acetate:methanol=95:5?v:v?was used as an elution solvent for solid phase extraction,and the LOD and LOQ of the method were 1.2-6.8?g/kg and 4.8-9.3?g/kg,respectively.The recoveries of the samples were83.4%-101.6%,and the RSD of intra-day and inter-day precision were0.9%-3.6%and 1.5%-4.3%,respectively.