Magnetic Nanomaterials Solid Phase Extraction And Multiphase Liquid-Liquid Extraction For Detection Of Organic Hazardous Substances In Biological Samples

Mycotoxins and biogenic amines,as organic harmful substances,are widely present in biological samples These substances content are extremely low and the matrix of biological samples is complicated,which make the analysis and detection of organic harmful substances more difficult.Some traditional Chinese medicine and tuna are regarded as health food and nourishment.Once consumers consume products contaminated with organic harmful substances,they will endanger health.In this paper,Mycotoxins and biogenic amines were used as research objects.High performance liquid chromatography（HPLC）was used to optimize the performance of mycotoxin multiphase extraction and to explore the interaction mechanism between magnetic materials and biogenic amines in tuna.An analytical method for the mycotoxin in Chinese tuna and the biogenic amine in tuna was established,respectively.The main contents are as follows:1.An analytical method for the simultaneous determination of eight mycotoxins by high performance liquid chromatography-ultraviolet tandem fluorescence detector was developed.Elution was carried out with a methanol-acetonitrile-0.5%aqueous solution of acetic acid in a ternary mobile phase system.The eight toxins showed good linearity in the concentration range of 2.500²50.0μg/L,and the detection limit ranged from 0.3189 to 4.688μg/L.The mycotoxin in black beans,black sesame seeds and lotus seeds was determined,and aflatoxin AFB₁ was detected in black beans and lotus seeds at contents of 3.9μg/kg and 2.6μg/kg,respectively.2.The sample was pretreated by the aqueous two-phase extraction system,constructed by acetonitrile/ammoniumsulfate/water and combimed with the dispersive liquid liquid microextraction technique.The effects of extraction conditions on mycotoxins were studied.The extraction conditions were optimized by single factor experiment.The results of the best extraction conditions were:the acetonitrile content of the aqueous two-phase system was 34%,the ammonium sulfate content was 22%,the system pH was 6,the extraction temperature was 40°C,the ultrasonic extraction time was 10 min,and the extractant was 0.7 mL chloroform,the dispersant was 1 mL of the top phase.The enrichment factor is between2.64 and 8.10.The recovery rate of mycotoxins are between 88.2%and99.0%.The method was applied to extract lotus seeds,black beans,black sesame seeds,southern almonds and lychees.Among them,aflatoxin AFB₁was detected in lotus seeds,black beans and litchi,and the average contents were 2.9μg/kg,3.5μg/kg and 4.4μg/kg,respectively.AFB₂ was also detected in litchi,with an average content of 2.6μg/kg.3.Using dansyl chloride derivatization-reverse phase liquid chromatography,eluting with a gradient of methanol-acetonitrile-water solution ternary mobile phase system,shortening the analysis time to 45min,improving the detection sensitivity;optimizing the ammonia reaction time of the terminator is 20 min.The linearity is good in the concentration range of 0.1¹0 mg/L,the detection limit is in the range of 0.0026⁰.026mg/L.The method for the determination of nine biogenic amines were established to apply to the detection of biogenic amines in tuna.The biogenic amine content ranges from 0.01090 to 1.405 mg/kg,and the RSD ranges from 2.3%to 3.4%.4.Ultrasound-assisted reverse co-precipitation method was used to prepare Fe₃O₄.The optimum conditions were ultrasonic frequency,ultrasonic power and reaction temperature.The best conditions were:ultrasonic frequency 20 KHz,ultrasonic power 140 W,reaction temperature 60°C,the particle size of Fe₃O₄ is 204±19 nm.The Fe₃O₄-SiO₂ particle size is 439.8±23.4 nm,and the silica layer is about 200nm.The adsorption performance of Fe₃O₄-SiO₂ and the elution effect of different concentrations of hydrochloric acid were studied.The results show that the Fe₃O₄-SiO₂ magnetic material synthesized by tetramethyl orthosilicate has the best adsorption rate at pH=10 and 50°C and.Except for octamine,the adsorption rates of the other 8 kinds of biogenic amines were above 85%;the elution rate of 5 mol/L hydrochloric acid was the best,the elution rate was over 80%,the method enrichment factor is around 5.The method is applied to the detection of tuna biogenic amines,the content ranges from 0.01080 to 1.321 mg/kg,the RSD ranges from 3.2%to 5.3%.5.3-Aminopropyltriethoxysilane（APTES）and glutaric anhydride were reacted with magnetic materials to modify the surface of Fe3O4-SiO2to prepare carboxyl functionalized magnetic nanomaterials for solid phase extraction of amines.The content of the octopamine in tuna was determined by liquid chromatography.The adsorption rate of the amines of Fe₃O₄-SiO₂-COOH prepared by 200 mg was increased to 75.27%.The method was applied to the detection of actual tuna samples,and the recovery rate was increased to 86.23%.