Studies Of γ-Fe₂O₃ Magnetic Nanoparticles In Amino Acid Extraction Of Magneto-solid Phases

This paper aims to study the magnetic solid phase extraction of l-phenylalanine,L-glutamate and L-lysine byγ-Fe₂O₃magnetic nanomaterials,so as to judge the feasibility of magnetic solid phase extraction of amino acids byγ-Fe₂O₃magnetic nanomaterials.The surface ofγ-Fe₂O₃was modified by cysteamine,polyethylene imine（PEI）,3-aminopropyl trimethoxysilane（APTMS）and polyaminoamine dendrimer（PAMAM）.γ-Fe₂O₃was first coated with Si O₂,and then functionalized on the surface ofγ-Fe₂O₃@Si O₂material to prepare four amino-functionalγ-Fe₂O₃magnetic nanomaterials,namelyγ-Fe₂O₃@Si O₂-cysteamine,γ-Fe₂O₃@Si O₂-PEI,γ-Fe₂O₃@Si O₂-APTMS,γ-Fe₂O₃@Si O₂-G1.0.The modified four magnetic nanomaterials were characterized by Fourier transform infrared spectroscopy（FTIR）,X-ray p Hotoelectron spectroscopy（XPS）,and transmission electron microscopy（TEM）images to prove that the aminoylation surface modification ofγ-Fe₂O₃was successful.Afterwards,the magnetic solid phase extraction experiments of l-phenylalanine,L-glutamic acid and L-lysine were carried out by using the four kinds of amino functionalized magnetic nanomaterials,and the concentration gradient,p H gradient and extraction time gradient of amino acid solution were optimized.The adsorption time gradient was set as 0.5h,1h,2h,4h,8h,and the p H value gradient was set as 3,5,7,9,11.The concentration gradient of amino acid solution was set as 2.5×10^-6mol/L,5.0×10^-6mol/L,7.5×10^-6mol/L,1.0×10^-5mol/L and1.25×10^-5mol/L.The fluorescence intensity of supernatant was measured by fluorescence spectrop Hotometer.The lower the fluorescence intensity,the better the adsorption effect of nanomaterials.According to the results,the extraction effect is the same in the concentration gradient interval,which indicates that the concentration of amino acid solution in this concentration interval does not affect the extraction effect,and also indicates that the magnetic nanomaterial functionalized by amino acid has a high extraction sensitivity for amino acid.The results of p H value and extraction time of amino acid solution showed thatγ-Fe₂O₃@Si O₂-G1.0material has the best extraction effect on L-phenylalanine,followed byγ-Fe₂O₃@Si O₂-PEI material;γ-Fe₂O₃@Si O₂-PEI material The extraction effect of L-glutamic acid and L-lysine is the best,followed byγ-Fe₂O₃@Si O₂-cysteine material,soγ-Fe₂O₃@Si O₂-PEI material is more suitable for magnetic solid phase extraction of amino acid solution.For the elution of L-p Henylalanine,1%SDS solution and 0.1mol/L HCl solution had the best elution effect,followed by anhydrous methanol.For the elution of L-glutamate,1%SDS solution had the best elution effect,followed by l-lysine.The best eluent was 1%SDS solution,followed by anhydrous methanol.