Comparative Of Analysis Methods For Quinolones Antibacterials In Food

The pollution of heavy metals is a dominant factor jeopardizing the public health. With the rapid development in science and technology and proceeding industrialization, heavy metal pollution has been an important problem of food safe. Thus, to efficiently monitor heavy metal pollution has become one major task.Because of high complexity of heavy metal classification, low concentration and severe interference caused by matrix effects, traditional analytical methods were not competent for challenging. Although many instrument analysis methods possessing higher sensitivity and selectivity have been developed recently, there isn't a further popularization in the middle-and-small food businesses in China because of the high cost. So, the spectrophotometers become the main and economic instrument for determination of heavy metals. The detection limit of spectrophotometers is high, but the time effectiveness, sensitivity and specificity of the spectrophotometry can be improved with the pre-concentration and effective separation of heavy metals. The results obtained with this method can meet the requirements of other instruments.In this paper, research on crosslinked polystyrene matrix resins and these adsorption to metal ions were reviewed, and the preparation of a series of crosslinked polystyrene matrix resins as well as these adsorption performance which were studied by researchers were enumerated. Aim at separation and preconcentration of metals, some resins were synthesized by anchoring heterocyclic and straight-chain ligands into crosslinked polystyrene. The adsorption behaviors to metal ions were studied. Subsequently, a new method of determination of heavy metals by spectrophotometry is proposed for using chelating resins in preconcentration and separation in tea.1. In this thesis, six kinds of chelating resins with heterocyclic and straight-chain ligands were prepared. The influences of various reaction conditions such as reaction solvent, reaction temperature and molar ratio of reagents on the quality of resins were studied. The N content of the resins, the functional group capacities and percentages of functional group conversation of the resins were determined by elemental analysis. The resin structures were confirmed by IR. 2. The adsorption properties of six resins for heavy metals were systematically investigated by means of static and dynamic method. The experimental results with static method showed the resins possessed excellent selectivity, such as TZR for Pb²⁺, 5-ATMDR for Ni²⁺, EDR for Cu²⁺. The statically saturated adsorption capacity of resins was 174 mg/g, 169 mg/g, 237mg/g, respectively. The elution percentage could be up to 100%. Kinetics functions, thermodynamics functions and the adsorption isotherms in different temperature were studied. The results were fitted for Langmuir and Freundlich equations. The adsorption process followed with pseudo-first-order kinetics. The adsorption process was endothermic and a complex interaction of physical and chemical factors. From the study of dynamic adsorption, the dynamic saturated adsorption capacity of resins as follows: 5-ATMDR for Ni²⁺, TZR for Pb²⁺, EDR for Cu²⁺ were 195 mg/g, 208mg/g, 245 mg/g, respectively. Dynamic adsorption coincided with Thomas model. Metal ions adsorbed on resins could be eluted completely. And resins had favorable repetitive property.3. Applying chelating resin enriched heavy metals to detect heavy metal contents in tea was proved available by comparison with experimental data from FAAS.