Study On Molecularly Imprinted Fluorescence Analysis For The Detection Of Alpha-cypermethrin

Alpha-cypermethrin(a-CPM)is a pyrethroid insecticide which has been increasingly used in the agriculture industry due to its remarkable advantages such as high efficiency and enduring efficacy.Since the wide and coutinuous utilization of a-CPM,its residue existed in foods and environment can cause environmental contamination and human-health problems.Recently,many analytical methods including high-performance liquid chromatography(HPLC),gas chromatography(GC)and gas chromatography-mass spectrometry(GC-MS)have been employed for quantitative determination of a-CPM.However,these conventional methods suffer from time-consuming,complex pretreatments and expensive instruments.It is thus urgent to develop a method that can be used in detecting a-CPM in real samples with solid reliability,extraordinary rapidity and certain convenience.In this work,a novel sensitive molecularly imprinted fluorescent nanosensor based on metal-organic frameworks and upconversion nanoparticles was developed for trace determination of ?-CPM.The main steps of this method are as follows.Firstly,the lanthanide ion doped photon-upconverting nanoparticles(UCNPs)with unique optical properties were synthesized by thermal decomposition method.The ZIF-8 was introduced then to improve the mass transfer and adsorption capacity of the composite material(UCNPs@ZIF-8).Next,the UCNPs@ZIF-8@MIP was prepared in mixed solutions containing UCNPs@ZIF-8(support material),a-CPM(template),AM(functional monomer)and DVB(cross-linker).Finally,the morphology and structure of UCNPs,UCNPs@ZIF-8,MIP and NIP were characterized by transmission electron microscopy(TEM),fourier transform infrared(FT-IR)and X-ray powder diffraction(XRD).As the density of a-CPM increases under the optimal condition,the fluorescence intensity of MIP decreases linearly,and the resulted linear range is 0.10-12 mg L-1.The corresponding standard linear equation is F0/F?0.029[Q]+1.007,in which,the linear correlation coefficient r2 is 0.998,and the limit of detection(LOD)is 0.03 mg L-1.To prove the validation of the prepared probe,The probe was used to detect the a-CPM in real samples,satisfactory results were obtained compared with that from the GC-MS method.The above result clearly shows that the proposed nanosensor has enormously potential applications in the food safety.