Development New Methods For Analysis Of Food Additives

A method for simultaneous detection of food additives by High Performance Liquid Chromatography(HPLC)was developed.To improve the detection sensitivity,high efficiency sample preparation technique is usually required.The magnetic Fe3O4@GO nanocomposite was prepared and characterized by scanning electron microscope(SEM),infrared spectroscopy(IR),X-ray diffraction(XRD),vibrating sample magnetometer(VSM)and Brunauer-Emmett-Teller(BET).The as-prepared nanomaterial was used as adsorbent for extraction and preconcentration of flavors and fragrances in foods.A rapid,high-resolution and effective new method for analyzing food additives analysis was established.This thesis consists of four chapters,the main content presented following:In chapter 1,food additives and the types were generally introduced,several conventional food additives and their effects,some pre-treatment methods and detection technology for food additives analysis were described.And the purpose and signification of this thesis were described,too.In chapter 2,a method for the analysis of antioxidant and preservative including propyl gallate(PG),tert-Butylhydroquinone(TBHQ),butylated hydroxytoluene(BHT)and benzoic acid in foods by HPLC was developed.The chromatographic conditions including mobile phase,flow rate,column temperature were investigated.Under the optimized conditions,the linearity range of the developed method for the analysis of PG,benzoic acid,TBHQ,BHT were 1-200,2-400,2-400 and 0.5-400 μg/m L with correlation coefficients(R2)not lower than 0.9994.The limits of detection(LODs)were in the range of 0.02-0.06 μg/m L at a signal-to-noise ratio of 3,the recoveries of these compounds were in the range of 77.76-106.27%.The developed method was also applied to analysis real samples.In chapter 3,the GO was prepared according to Hummers’ method with a modification,and Fe3O4@GO nanocomposite was prepared via a simple one-step co-precipitation strategy and used as sorbent of SPE.The magnetic Fe3O4@GO nanocomposite was characterized by scanning electron microscope(SEM),infrared spectroscopy(IR),X-ray diffraction(XRD),vibrating sample magnetometer(VSM)and Brunauer-Emmett-Teller(BET).The as-prepared nanomaterial has some merits including high surface area,superparamagnetic properties,strong magnetism and so on.The extraction and desorption conditions including amount of materials,extraction time and desorption solvents were investigated.In chapter 4,the as-prepared Fe3O4@GO nanocomposite was used as adsorbent for extraction and preconcentration of flavors and fragrances in foods.A method for the analysis of flavors and fragrances including ethyl vanillin,trans-cinnamic acid,methyl cinnamate,ethyl cinnamate,and benzyl cinnamate in foods by HPLC with Fe3O4@GO nanocomposite as the adsorbent of magnetic solid-phase extraction was developed.All of the analytes exhibited satisfactory linearity with correlation coefficients(R2)between 0.9993 and 0.9999.The LODs of 0.02-0.04 μg/m L for the analytes were obtained,based on the ratio of signal-to-noise(S/N=3)with the RSDs(n=5)lower than 3.49%.To further evaluate the practical applicability of the established MSPE-HPLC method,orange juice,chocolate and fruit sugar were detected as real samples to analysis.With the developed method,ethyl vanillin(0.33 μg/m L)and benzyl cinnamate(1.37 μg/m L)were detected in orange juice,ethyl vanillin(1.563 μg/g)was detected in chocolate,and benzyl cinnamate(0.22 μg/g)was detected in fruit sugar.The recoveries of the established method for the analysis of flavors and fragrances were investigated by spiking three different concentrations of analytes to the orange juice.The recovery obtained from the analysis of spiked juice sample was between 71.5% and 112.4% with RSDs lower than 4.14%.The developed method was successfully applied to the analysis of real samples including orange juice,chocolate and fruit sugar.Experimental results demonstrated that a detectable reduction in the extraction efficiency was not observed when the Fe3O4@GO material was reused 5 times.The developed MSPE method possessed excellent extraction efficiency and comparable stability compared with commercial C18 SPE column and other reported work.