Preparation Of Graphene Oxide Composites And Detection Methods Of Plant Growth Regulators

Plant growth regulators are a class of pesticides used to regulate plant growth and development which are widely used in agricultural production.The abuse of plant growth regulators can lead to the appearance of hollow and hard fruits,fruit and vegetable malformations and plant death.In addition,more plant growth regulators in fruits and vegetables can threaten human health,such as genotoxicity,neurotoxicity and immunotoxicity.Plant growth regulators in fruits and vegetables are low in content and complex in matrix.Therefore,the development of a simple and rapid pretreatment method is significant for the determination of low-concentration plant growth regulator residues in fruits and vegetables.Solid phase extraction is one of the commonly used methods in sample pretreatment,because it is fast and easy to operate and suitable for many fields such as food,environment and medicine.The core of solid phase extraction is the selection and preparation of adsorbents,which is directly related to the extraction efficiencies.Therefore,the research and development of new adsorbent materials has become an important development direction of sample pretreatment.In the first chapter,the current sample pretreatment methods for detecting plant growth regulator were summarized mainly include liquid-liquid microextraction,accelerated solvent extraction,ultrasonic extraction,microwave-assisted extraction and solid phase extraction.The development and application of graphene materials,molecularly imprinted materials and graphene molecularly imprinted materials in solid phase extraction were also introduced.In the second chapter,using the large specific surface area of graphene oxide and abundantoxygen-containingfunctionalgroups,thesilicon-oxygenbondin3-aminopropyltriethoxysilane and the hydroxyl group on the surface of graphene oxide are coupled by coupling reaction.The synthetic material is used as a adsorbent,combined with pipette-tip solid-phase extraction to determine kinetin and 6-benzyl adenine in tomato sample.The detection limits and quantification ranges of the two targets were 0.013-0.027?g g^-1 and0.044-0.090?g g^-1,and the recoveries were 89.7%-97.2%?RSD?2.0%?.This method can be used for the detection of kinetin and 6-benzyl adenine in tomato products.In the third chapter,utilizes the large specific surface area of graphene oxide materials and the specific selectivity of molecularly imprinted polymers,a novel composite material was prepared by using an amino-functionalized graphene oxide material as the substrate and modified by surface molecular imprinting.The parameters were optimized mainly including the monomer dosage,template dosage,crosslinking agent dosage,and reaction time.The obtained material is used as a adsorbent,combined with pipette-tip solid-phase extraction to detect naphthylacetamide,naphthaleneacetic acid and naphthoxyacetic acid in apple samples.The detection limits and quantification ranges of the three plant growth regulators were0.21-0.53 ng g^-1 and 0.70-1.8 ng g^-1,and the recovery was 87.6%-99.5%?RSD?3.5%?.This method can be used to detect three plant growth regulators in apples.