| The problem of pesticide residues has always been a hot issue in the field of analytical chemistry.As an important class of synthetic pesticides,Pyrethroid pesticides compared with traditional organochlorine pesticides,has a broad spectrum,can be used for the prevention and control of a variety of crop diseases and insect pests,and high efficiency and low toxicity Over the years,organic chlorine and organophosphorus pesticides have been gradually replaced and used for pest control in agriculture and forestry.Pyrethroids can seriously interfere with the endocrine system of humans and animals,thereby inducing various diseases and causing carcinogenicity of the body.Improper use can lead to higher residues,which seriously threatens human health.Tea,as a traditional Chinese beverage,contains pesticide residues that directly affect human health.Pyrethroid pesticide residues in tea are a topic of general concern to researchers.In order to protect human health and reduce the pollution degree of pyrethroid pesticides to the environment,society has put forward higher and higher requirements for the content of pyrethroid pesticides in food.Therefore,it is necessary to develop an efficient and highly sensitive method for the determination of pyrethroid pesticide residues.However,due to the low content of pyrethroid pesticides in the tea,the content needs to be enriched in advance during the measurement.Therefore,this experiment intends to design a set of methods that integrate enrichment and determination to determine the content of pyrethroid pesticides in tea samples.After conducting literature research in this paper,based on the research status of pesticide residues in tea at home and abroad,some modern enrichment extraction and analysis techniques were applied to establish a new method for the determination of five pyrethroid pesticide residues in tea.The research content mainly includes:1.A carbonyl iron powder bonded silica monolithic column was prepared for the enrichment and extraction of pyrethroid pesticide residues,and combined with GC-MS/MS method to establish online enrichment and thermal desorption GC-MS/MS Determination of pyrethroid pesticide residues in tea samples.The hydroxyl-terminated polydimethylsiloxane is covalently bonded to the surface of the SiO2 network,and at the same time is bonded to the carbonyl iron powder.After the target analyte was adsorbed and concentrated on the polydimethylsiloxane site,the high-frequency induction heating technology was used to successfully achieve GC-MS/MS direct gas sampling.The experimental results show that under the best conditions,the detection limit of pyrethroid pesticide residues is 3.8～7.5 μg/kg,and the relative standard deviation(RSD)is 3.2%～6.8%(n=6).The extraction recovery rate and correlation coefficient of this method are 97.7%～110.5%and 0.9973,respectively.Under optimal conditions,the enrichment factor of this method can reach about 1,000 times.2.On the basis of the hybrid monolithic column,combined with surface molecular imprinting technology,using m-phenoxybenzoic acid(PBA)as the template molecule,five general purpose pyrethroid pesticides represented by permethrin were prepared Magnetic molecularly imprinted polymer materials,combined with a self-made hybrid solid phase extraction monolithic column,were used to enrich and separate the pyrethroid pesticide residues in tea.A new method of pyrethroid pesticides in tea.The experimental analysis analyzes the optimization of the conditions in the preparation process of magnetic molecular imprinting materials,and evaluates the performance parameters such as enrichment factor,detection limit(LOD)and recovery rate.The results show that under the best conditions,the detection limit of the method is 3.5～7.8 μg/kg,RSD is 2.8～6.6%(n=6),and the extraction recovery rate and correlation coefficient can reach 98.3%～109.8%and 0.9971.Under optimal conditions,the enrichment factor of this method can reach about 1,000 times. |
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