Application Of Liquid Chromatography And Its Hyphenated Techniques In The Analysis Of Pesticide Residues In Food And Environment

The development and utilization of pesticides increase the yield and quality of agricultural products,however,the excessive pesticide residues caused by improper use or even abuse also poses a major hidden danger to human health,environment and agricultural trade.Strengthening pesticide residues testing is an important technical guarantee for food safety and environment protection.The detection of pesticide residues in food and environment has the characteristics of low content and complex matrix.Therefore,the development of efficient,rapid and sensitive sample preparation methods and analytical techniques are of great significance for the detection of pesticide residues in food and the environment.In this paper,QuEChERS and molecular imprinting techniques,combined with liquid chromatography and its hyphenated techniques,were used to establish new methods for the analysis of trace pesticide residues in food and environment.The new methods have been applied to the determination of real samples with satisfactory results.The main research results are as follows:1.A new and reliable method for the simultaneous determination of nineteen plant growth regulators(PGRs)in fruits and vegetables by QuEChERS-UPLC-Q-TOF-MS/MS was proposed.The samples were initially extracted with acetic acid-acetonitrile(1:99,V/V),the extracts were cleaned with adsorbents ostade-cylsilane(C18),primary secondary amine(PSA)and graphitized carbon black(GCB)),and then separated on a C18 column.The identification of each compound was established by retention time matching along with the accurate mass measurement of the precursor ions and their main fragment ions.The quantification was carried out using matrix-matched external standard method.Under the optimized conditions,the limits of detection for the 19 PGRs ranged from 0.03 to 14 ?g/kg,the recoveries were in the range of 70.1%?116.0%,with the RSD<10.6%.The proposed procedure was simple,quick and accurate for the simultaneous determination of the 19 plant growth regulator residues in fruits and vegetables.2.Dichloroquinolinic acid molecularly imprinted polymer(MIP)was synthesized using dichloroquinolinic acid as template molecule and 4-vinylpyridine as functional monomer in N,N-dimethyl formamide solvent.The synthesized material was characterized by Fourier transform infrared spectroscopy,scanning electron microscopy,specific surface and porosity tester Using the MIP as selective solid phase extraction sorbents and HPLC-UV as analytical technique,a new and simple method for the determination of trace dichloroquinolinic acid residues was established.The adsorption and desorption conditions of MIP were optimized.The results showed that under the conditions of pH 2.5 aqueous phase,adsorption time 10 min,dosage of the absorbent 30 mg,the material has good adsorption of dichloroquinolinic acid.With methanol:acetic acid=9:1(V/V),dichloroquinolinic acid may well be desorbed from the MIP.The proposed method was applied to the determination of dichloroquinolinic acid residues in paddy water and brown rice samples with spiked recoveries of 71.0%?108.0%and the RSD of 2.0%?11.8%.The limit of method detection of brown rice was 0.16 mg/kg,which is much lower than the national limited standard of 1 mg/kg.3.Phenoxyacetic acid-specific molecularly imprinted polymer(MIP)was synthesized using phenoxyacetic acid as template molecule and 4-vinylpyridine as functional monomer in acetonitrile solvent.The synthesized material was characterized by Fourier transform infrared spectroscopy,scanning electron microscopy,specific surface and porosity tester Using the MIP as selective solid phase extraction sorbents for p-chlorophenoxyacetic acid,4-iodophenoxyacetic acid,cloprop and 2,4-D,which have a similar structure to phenoxyacetic acid,and HPLC-UV as analytical technique,a new and simple method for the determination of the for four phenoxyacetic acid pesticides was established.Because the MIP was prepared with pseudo template molecule,it effectively overcome the problem of template leakage.Meanwhile,it also has good selectivity for the four target compounds.The proposed method has been applied to the determination of the above four pesticide residues in mung bean sprout samples with satisfied results.