Study On The New Methods And Their Applications In The Separation/Enrichment/Analysis Of Antibiotic

Antibiotics have been extensively used in disease prevention,control and treatment of livestock and poultry, aquatic animal and plant due to their broad range of activity against bacteria and their economic advantages. The residual substances of antibiotics which enter into the environment via various channels are toxic and difficult to biodegradation. Antibiotics in the soil, plants,food and animal waste would eventually enter the natural water body, and that,the residue of antibiotics would be transfered to flora,fauna and human body from water. This is a serious threat for the natural ecological balance system and human health. To detect these antibiotics, the new integrated.analysis methods which combines separation and collection with analysis are needed.The aim of the project was to develop fast and reliable methods, consisting of aqueous two phase-solvent sublation, charge transfer SpectroPhotometry and of Molecular Imprinting Technique, for the separation/enrichment of antibiotic in environment samples. The aim of the research is to build a foundation of theory and practice for controlling the pollution of antibiotics residues. The main research contents and conclusion are as follows:1. The separation/enrichment of roxithromycin was studied based on the system of aqueous two phase-gas solvent subblation, and the method of sulfuric acid color was established to determin roxithromycin enriched. The optimal condition of the solvent sublation was obtained:the sublation solvent was isopropanol, the salting-out agent was K2HPO4 with 48%(g/100ml),the pH was 9, N2 flow rate was 15 ml/min, the sublation time was 30 min.The flotation efficiency under the optimum conditions was 93%, enrichment multiple was 9.3. And compared with the solvent extration, the solvent sublation was better.2. The separation/enrichment of tilmicosin was studied based on the system of aqueous two phase-gas solvent subblation, the method of HPLC was established to determin tilmicosin enriched. The optimal condition of the solvent sublation was obtained:the sublation solvent was n-propanol, the salting-out agent was (NH4)2SO4 with 36%(g/100ml),the pH was 3, N2 flow rate was 20 ml/min, the sublation time was 30 min.The flotation efficiency under the optimum conditions was 84%, enrichment multiple was 16.8. And compared with the solvent extration, the solvent sublation had many merits, such as high enrichment factor, large volume of water sample, n-propanol with less, no emulsification, etc. The method is suitable for determining the antibiotics residue in environment sample.3. The charge-transfer (CT) reaction between roxithromycin as the electron donor and iodine as the electron accepter has been studied by spectrophotometric method. The experiments indicated that in alcohol solution can form charge transfer complex with iodine, the composition ratio was 1:1.5,λmax was at 290,360nm, the absorbance was linearly related to the concentration of roxithromycin in the range of 2～500 mg/L. The proposed method has been applied to the determination of roxithromycin in capsules and dispersible tablets, the results are in good agreement with the official method. The recovery of roxithromycin was over 96.2%～101.94%.4. A spectrophotometry method for the detemination of erythomycin has been developed based on the charge transfer reaction between erythomycin as donor and methylene blue as acceptor in this paper. The rection was achieved with good results in water solution.The apparent molar obsorptivity of complex at 678 nm is 1.59×104L/(mol·cm). The Beer's law was hold in the range of 0.0008～0.0250 mg/ml of erythomycin. Detection limit of this method was found to be 0.11μg/ml. The composition of the charge transfer complex between erythomycin and methylene blue is 1:1. The present method has been applied to the determination of erythomycin in capsules with satisfactory results.5. Molecularly imprinted polymer microspheres of Gatifloxacin were prepared by precipitation polymerization in this experiment. UV spectrophotometry was used to study the adsorption properties of molecularly imprinted polymer microspheres. The microscopic appearance and morphology of molecularly imprinted polymer microspheres were characterized by scanning electron mocroscopy. The results of the research show that the adsorption properties of molecularly imprinted were a little better than that of molecularly imprinted polymers which were prepared by the traditional bulk polymerization. The preparation process of precipitation polymerization was relatively simple and time-saving and obviated the grinding, sieving and other tedious post-processing procedures.6. A tilmicosin molecularly imprinted polymer (MIP) grafted on modified ordered mesoporous silica SBA-15 was prepared via surface molecularly imprinting technique. The prepared polymer was characterized by Raman spectrometry and scanning electron microscopy (SEM). The adsorption behavior of adsorbent for tilmicosin was investigated using batch experiments. The MIP exhibited fast kinetics, high adsorption capacity for tilmicosin due to its high surface area providing imprinted sites. Under the optimum experimental condition, tilmicosin adsorption process over tilmicosin -MIP followed pseudo-second-order reaction kinetics and the Langmuir adsorption isotherm. In addition, the thermodynamic parameters calculated from the adsorption data suggested that the adsorption of tilmicosin onto MIP was an endothermic nature of the process.7. The novel molecular·imprinted polymers with tilmicosin as the template molecule were prepared based on modified ordered mesoporous silica SBA-15 with surface imprinting technique. These imprinted polymers were applied as solid-phase extraction materials for selective extraction of tilmicosin from water matrixes. Different experimental variables (sample solvent, eluent and eluent volume, etc.) associated with the rebinding/elution process were optimized. Moreover, the imprinted polymers were used as materials of solid phase extraction to test residues of tilmicosin in environment. Molecularly imprinted solid-phase extraction (MISPE) with high selectivity have been recognized as useful tools for detection the residues in environment.