| Food safety has become a major concern of the society in recent years. In order to make improvement in human health and environment protection, it is quite necessary and of great significance to do the research on determination of harmful residues in foods, food additives, packaging materials and aquatic environment for protection of human health and prevention of food contamination.In this thesis determination of four kinds of hazardous organic substances in foods and related materials were investigated, which are considered as very important parts of food safety project.First, research on determination of volatile impurities such as dichloromethane, chloroform, benzene, trichloroethylene, and 1,4-dioxane in saccharin sodium, benzoate sodium and citric acid food additive using solid phase microextraction technique was studied. The polydimethylsilicane (PDMS) fiber was used to extract the target components. The analytical column was HP-5 and the detector was flame ionized detector (FID). The conditions of SPME were optimized and the recoveries of the five harmful impurities were in the ranges between 97.3%～103.9.Second, trace amounts of 2, 3-butanedione and styrene in the edible alcohol and brewed products were determined by gas chromatography/mass spectrometry (GC/MS) technique. A new type of HP-PLOT U capillary column was used for the separation of 2, 3-butanedione and styrene. The results show that 2,3-butanedione styrene and alcohol can be baseline separated. The recoveries of the method were between 94.0%～105.0%.Third, two test methods using gas chromatograph/mass (GC/MS) or liquid chromatograph-mass/mass (LC-MS/MS) for the determination of perflurooctanoic acid (PFOA) and its salts in packaging materials were established. Accelerated solvent extraction (ASE) technique was used to extract perflurooctanoic acid (PFOA) and its salts from packaging materials. After filtration and concentration, the extract could be directly quantified by liquid chromatography-mass/mass (LC-MS-MS) method. When GC/MS was used, the derivation of the extract with NaBEt4 was needed before the sample was analyzed, and the perflurodecanoic acid(PFDA) was used as an internal standard. The established methods was employed for detecting 14 kinds of packaging materials, in which a kind of polytertfluroethylene (PTFE) film was detected to contain PFOA and its salts, and the content was 0.13ng/g.Finally, a new rapid and green method of off-line supercritical fluid extraction (SFE) /headspace solid-phase microextraction (/HS-SPME) / GC/MS was established for the determination of organotin compounds in clam, kelp samples. The optimization of SFE and HS-SPME conditions was conducted. SFE extract was ethylated with 1% (w/v) sodium tetraethylborate (NaBEt4) in pH 4 buffer solution and simultaneously adsorbed by HS-SPME with polydimethylsiloxane-divinylbenzene (PDMS/DVB) fiber at 50℃for 30 min, and then GC/MS quantification was performed. Precision, limits of detection (LOD), and linear range of the method established can meet quantification of five kinds of organotin compounds in biotic sample.A theoretical model proposed by Jiu Ai for dealing with solid phase microextraction for quantitative analysis in nonequilibrium situations was tested by experimental and theoretical studies in order to verify its suitability, where five hydrous solution of volatile organic substances of CH2Cl2,CHCl3,C6H6,C2H4Cl3 and C4H8O2 were used as tested systems. The results show that a linearly proportional relationship exists between the adsorbed analyte and its initial concentration in the sample matrix before adsorption equilibrium was attained, in which the ranges of the initial concentration and adsorption time have obviously influences on the linear relationship which depends on the tested systems.
|
PDF Full Text Request