Preparation And Properties Analysis Of Composite Separating Materials Based On Poly(MAA-co-EDMA) Monolithic Column

Due to the characteristics of the matrix effect, the coexistence of variouscomponents, and the complexity of biological samples in food safety monitoring,environment monitoring and biochemical analysis, how to obtain the effectivecomponents and its efficient detecting have become one of the most important step inmonitoring process. So the sample pretreatment technology must come first in thisprocess. Compared with other pretreatment technology, SPE (Solid Phase Extraction,SPE) is the most commonly used at present because of flexible processing medium andoperation mode, simple operation and easily automated. However, the medium materialtype and effectiveness of solid phase separation is limited. Therefore, developing newtype of solid phase separation medium material for effective sample pretreatment andanalysis has a broad prospect. Based on the principles of solid phase extraction,solid-liquid two-phase chromatographic monolithic column separation, the selectiverecognition of molecularly imprinted technology and the surface modification ofnanomaterials, a seris of novel efficient pretreatment materials is proposed, studied andapplied in pesticide analysis, laying the foundation for the detection of pesticideresidues in real samples.(1) Based on the monolithic column of good separation effect and graphene oxideof large specific surface area and high adsorption efficiency, a new type of separationcomposite materials (PVP-GO/MC) is successfully prepared by in-situ polymerizationthrough incorporating PVP-GO during the preparation of Poly (MAA-co-EDMA)Monolithic Column. Under the optimizated condition of the solid phase extraction(sample volume of1.5mL,0.15mL·min-1sample flow rate, acetonitrile (1%acetic acid)as the elution solvent,0.05mL·min-1elution flow rate, elution volume of0.15mL), theconcentration peak area of PVP-GO/MC is2.56times and6.73times than MC, forimidacloprid and chlorpyrifos, respectively. At the same time, the linear equations ofimidacloprid and chlorpyrifos are y=142.07x+5.5373and y=1272.4x+4.8429; thecorrelation coefficients are0.9991and0.9942; the detection limits are0.06μg·mL-1and0.004μg·mL-1by HPLC. By recovery experiment, the results show that the recovery rateof imidacloprid and chlorpyrifos are in the range of96.7%~110.0%and92.0%~102.5%.(2) Based on PVP-GO/MC material, a new composite separation material(PVP-GO/MIPMC) is prepared by in-situ radical polymerization through adding imidacloprid template molecule in the polymer matrix with MAA as monomer, EDMAas crosslinking agent, and graphene oxide as modified nanometer materials. ForN-nitroso glyphosate, the enrichment peak area of PVP-GO/MIPMC is essentially thesame as the area of PVP-GO/MC, and2.5times larger than the area of monollithiccolumn; for imidacloprid, the enrichment peak area of PVP-GO/MIPMC is1.26timesthan the area of PVP-GO/MC, and2.06times larger than the area of monolithic column.On this basis, the optimal separation conditions of high performance capillaryelectrophoresis are obtained. The linear equations of imidacloprid and N-nitrosoglyphosate, respectively, are y=553x+305.21and y=1913.6x+740.11; the linear rangesare1.0-20.0μg·mL-1and0.5-10.0μg·mL-1; the correlation coefficients are0.9893and0.9883; the detection limits are0.6μg·mL-1and0.3μg·mL-1. By recovery experiment inflour, the results show that the recovery rate of imidacloprid and N-nitroso glyphosateare in the range of83.0%~112.0%and94.0%~104.0%.(3) Based on PVP-GO/MIPMC material, a new type of composite material(MIPs/RGO) is prepared by dropping molecularly imprinted polymer (MIPs) on RGO.MIPs is prepared by bulk polymerization with imidacloprid as template molecule, MAAas functional monomer, and EDMA as crosslinking agent. RGO is on the GCE. Theimidacloprid current response of MIPs/RGO composites material is bigger thanNIPs/RGO material. At the same time, the imidacloprid current response ofMIPs/RGO-GCE is2.5times and3.3times than thiamethoxam and dinotefuran. Andacetamiprid and thiacloprid have no current response.In the range of0.5~70.0μMimidacloprid concentration, it has a good linear relationship; the linear equation andcorrelation coefficient are y=0.0879x+0.0841and0.9864; the detection limit is0.4μM(S/N=3). By the recovery experiment, the recovery rate and RSD%ofimidacloprid are in the range of95.5%~102.0%and3.4%~6.2%.