Preparation Of Molecularly Imprinted Polymeric Microspheres And Determination Of Some Hazardous Substances In Food By Capillary Electrophoresis

With the enhancement of people’s health awareness, people pay more and more attentionto the quality of food safety. Thus, it’s necessary to establish a method of simple, rapid,sensitive and reliable for the determination of hazardous substances in food.In this thesis, a new capillary electrophoresis(CE) method that applied to separation andanalysis of hazardous substances in food was developed; and a method of preparationmolecularly imprinted polymeric microspheres, which was suitable for preconcentrationhazardous substances in food, was investigated. Different sample processing methods wereinvestigated, and a simple and high-throughput method of ultrasonic extraction(USE)-CE wasdeveloped for determination of melamine in milk. The molecularly imprinted microsphereswere synthesized by suspension polymerization and were used as solid-phase extractionsorbent. The tetracyclines antibiotic residue in milk and phenols in water were determined bymolecularly imprinted solid-phase extraction(MISPE)-CE, respectively. A micellarelectrokinetic chromatographic method was developed for simultaneous determination of fivephytohormones in mung bean sprouts.Chapter1: The dangers of illegal additives and antibiotic residues in milk, the detectionmethods of additives and antibiotic residue and the application of molecularly imprintedsolid-phase extraction in food safety analysis were reviewed.Chapter2: Asimple, rapid, sensitive, and low cost method of USE-CE for determinationof melamine in milk was developed. The most widely used extraction methods aboutsolid-phase extraction and liquid liquid extraction were compared with USE by evaluatingsimplicity, cost and sample clean-up effect, etal. The conditions of CE were optimizeddetailedly. After extracted by simple extraction and centrifugation, the extract was analyzeddirectly. The proposed method demonstrated good performance concerninglinearity(r=0.9994), the precision was2.60-4.80%, the recovery was85.1-98.3%, and thelimit of method detection and quantifcation were0.163mg/kg and0.542mg/kg, respectively.Chapter3: The molecularly imprinted microspheres were synthesized using doxycyclineas the template molecule by suspension polymerization and were used as solid-phaseextraction sorbent. The tetracyclines antibiotic in milk were selectively enriched anddetermined by MISPE-CE, and better purification effect was obtained. The recovery was80.4-96.2%, the limit of method detection and quantification were2.36-2.59μg/kg and7.88-8.63μg/kg, respectively. Chapter4: A method of MISPE-CE was developed for the simultaneous determination ofphenol, resorcinol and p-nitrophenol in water samples. Under the optimized solid-phaseextraction conditions, the molecularly imprinted microspheres synthesized by suspensionpolymerization showed higher adsorption rate(95%) and enrichment times(33times) for thetemplate molecule. The limit of method detection and the recoveries were0.0488-0.809g/Land87.2%-100.4%, respectively. The intra-day(n=5) and inter-day(n=3) precisions were1.89%-5.63%and6.91%-8.14%, respectively.Chapter5: A simple and rapid micellar electrokinetic chromatographic method wasdeveloped for simultaneous determination of phytohormones in mung bean sprouts. Under theoptimized conditions, the method demonstrated good performance concerning linearity(r,0.9954-0.9991), the precision was0.77-4.97%, the recovery was83.6-102.6%, and the limitof method detection and quantifcation were0.011-0.177mg/kg and0.035-0.590mg/kg,respectively.