| Food is the only source of life and it offers invaluable advantages:growth and health promotion, energy, and disease prevention; hence, life will not exist without food. People like enjoying sharing meal-gathering together and like to taste different kinds of traditional cuisines; yet they also demand for consumption of quality and safe food. Principally, food, generally reconsidered as safe (GRAS), should be strictly produced from sanitations, good manufacturing practices, good handling practices, and good agriculture practices to conform with food safety system guideline in order to prevent the contamination or recontamination, especially microbial pathogens and toxic chemicals, because these materials cannot be visually detected. Food contaminations resulting to food poisonings are obviously very serious issues to public health, living welfare, and socio-economic development; therefore, they need to be tightly controlled (prevention, reduction, and elimination) before serving on the tables or markets. To tackle such these difficult problems is a main task and huge challenge for regulatory authorities, public health agencies, and food industries in order to ensure the quality and safe-to-eat food.Because of visually impossible detection of food hazards, numerous sophistically efficient analytical methods have been successfully developed in order to meet the growing demands for food safety and quality control and supervision. Although food toxicity mostly comes from pathogenic microbes, toxic chemicals; such as pesticide residues, illegal food additives, drug residues; are also a major threat to the life and public health; therefore, there is an increasingly considerable interest in developing new selective and sensitive method for extracting, isolating, and enriching contaminated components from complex food matrices. One of the promising methods that have been innovated so far is a molecularly imprinting technique, which has drawn a great attraction worldwide in the field of chemical separation science. The exploitation of this technique could produce a product of molecularly imprinted polymers (MIPs); which are very robustness, long-term stability, reliability, cost-efficiency, and selectivity; creating MIPs to gain more popularity in chemical separation and analysis.In this dissertation, we would like to introduce "an analytical method" using MIPs-based materials as a solid phase extraction for selective recognition of given chemical molecules from the food matrices before high performance liquid chromatographic determination. The technique of MIPs synthesis is based on a traditional method, which bulk MIPs need to be ground, sieved, and Soxhlet washed prior to applying them as a molecularly-imprinted solid-phase extraction (MISPE) for sample clean-up and enrichment. The main functional monomer and cross-linker we use in MIPs polymerization is ? (beta)-cyclodextrin, a 7-membered sugar ring molecule and ethylene glycol dimethacrylate (EGDMA), respectively. Our introduced method of MIPs polymerization is simple and inexpensive; moreover, the volume of organic solvent involved in the synthesis of MIPs and the rest of experimental process requires minimally, which is in parallel with environmentally-friendly way. Our findings are as follows.(1) In chapter two, we prepared a series of di (2-ethylhexyl) phthalate (DEHP) imprinted polymers by using the single use of allyl bromine-?-cyclodextrin (allyl-?-CD) and the combined use of allyl-P-CD and methacrylic acid (MAA), allyl-?-CD and methyl methacrylate (MMA), allyl-?-CD and acrylonitrile (AN), and allyl-P-CD and acrylamide (AA) as the binary functional monomers. The results proved that the binary functional monomers, except for AA monomer, are superior to a single monomer; their average bound substrate from binary monomers was ?110?mol g-1, whereas a single was ?90 ?mol g-1 in binding specificity. Finally, M-MAA, M-MMA and M-AN were chosen to run through molecularly imprinted solid-phase extraction (MISPE) to analyze the spiked infant formula of DEHP. For M-AN, the recovery ranged from 93.59-97.98% with relative standard deviations (RSD?3.21%).(2) In chapter three, we synthesized three kinds of clenbuterol-imprinted polymers by the combined use of ally-?-cyclodextrin (ally-?-CD) and methacrylic acid (MAA), allyl-?-CD and acrylonitrile (AN), and allyl-P-CD and methyl methacrylate (MMA) as the binary functional monomers. Based upon the results, M-MAA polymers generally proved to be an excellent selective extraction compared to its references:AN-linked allyl-?-CD MIPs (M-AN) and MMA-linked allyl-?-CD MIPs (M-MMA). M-MAA polymers were eventually chosen to run through a molecularly imprinted solid-phase extraction (MI-SPE) micro-column to enrich CLEN residues spiked in pork livers. A high recovery was achieved ranging from 91.03-96.76% with relative standard deviation (RSD?4.45%).(3) In chapter four, we exploited binary functional monomers, allyl-?-cyclodextrin (allyl-?-CD) and methacrylic acid (MAA) or allyl-P-CD and acrylonitrile (AN), in a fabrication of molecularly imprinted polymers (MIPs) for selective recognition and large enrichment of pirimicarb pesticide from aqueous media. According to the results, the effect of binding capacity of MAA-linked allyl-?-CD MIPs (M-MAA) demonstrated higher efficiency than that of AN-linked allyl-?-CD MIPs (M-AN) when tested in binding specificity. Finally, M-MAA was chosen to run through molecularly imprinted solid-phase extraction (MISPE) to analyze the spiked fresh leafy vegetables of pirimicarb. The present proposed technique is a promising tool for the preparation of the receptors which could recognize pirimicarb pesticide in aqueous media.According to the aforementioned results, we found that our synthesized MIPs could be used for a sample clean-up and pre-concentration of target analytes of interest in food matrices. Our MIPs showed good stability, good selectivity, and high efficient adsorption capacity towards the target molecules; therefore, they could be applied to real food samples as an integral part of analytical method for food quality and safety control and supervision.There are a variety of applications of MIPs such as off-line or on-line solid phase extraction (SPE), chemical and bio-sensors, catalysis, and drug delivery because MIPs, a synthetically potential artificial receptor-like binding sites with a "memory" for shape and functional group positions of the target molecule, possess a competent ability for selective specificity and recognition for target or unwanted chemical molecules. Among various MIPs applications, the most commonly used is an off-line solid phase extraction application due to its simplicity. Utilizations of MIPs-based materials have been applied to a wide range of chemicals, including food contaminants, pesticides, environmental pollutants, preservatives, and antibiotic drug residues for sample clean-up and pre-concentration, detection, and quantification.All in all, due to various functionalities of MIPs such as solid phase extraction (SPE), chemical and bio-sensors, catalysis, and drug delivery, molecular imprinting technique has drawn a huge attraction from a wide range of fields, including food safety, chemistry, biology, pharmaceutical engineering, and medicine, etc. MIPs have become a versatile tool of the modern analytical chemistry. |
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