Molecularly Imprinted Polymer's Application For Selective Determination Of Imidacloprid And Carbendazim In Fruits

China is the world's largest fruit producer and consumer,with apple,citrus,grape,pear and peach production ranking first in the world.There are many types of pests and diseases in fruit production,which occur frequently.At present,the main prevention and control measures include agricultural control,physical control,chemical control,biological control and comprehensive control.Among them,chemical control is the most effective for pest control in fruits.Insecticide imidacloprid and fungicide carbendazim are widely used in fruits.The use of chemical control can cause several problems,including pesticide residues,which result in causing hazardous health effects?low to chronic diseases?,disrupt the ecological balance,pest resistance,and economic losses;thus,pesticide detection is essential to protect consumer health and food quality and safety.Pre-treatment technology is important for the accurate detection of pesticide residues,and recently it got more attention because of austere foreign and domestic supervision,the maximum residue limits?MRLs?have been reduced,so trace level pesticide detection needs more efficient pre-treatment extraction techniques.At present,the pretreatment such as liquid-liquid extraction?LLE?,solid-phase extraction?SPE?,solid-phase microextraction?SPME?,and QuEChERS are widely used in the detection of pesticide residues in fruits.However,these techniques lack certain advantages like high sensitivity,sample matrix effect,or complex preparation.Molecular imprinting polymers?MIPs?have the advantages of specific binding ability,thermochemical stability,reusability,high sensitivity,and small matrix interference,which are more advantageous than other pretreatment methods.Here,two molecularly imprinted polymers were prepared by using methacryloyl chloride and?-cyclodextrin as functional monomers,respectively,and applied to the detection of imidacloprid and carbendazim residues in fruits.This work demonstrates the synthesis and characterization of core-shell magnetic molecular imprinting polymers based on surface imprinting using methacryloyl chloride as a functional monomer for the selective extraction of imidacloprid?template?from apple fruit.The characterization analysis results ensured the successful synthesis of the magnetic molecular imprinted polymers owing to their heterogeneous structure and good magnetic properties.An isothermal binding test was assessed with a pseudo-second-order kinetic model,and the kinetic results fit well to the Freundlich isothermal model.The polymers exhibited an adsorption capacity of 5.75 mg g^-1 for the target analyte with a good selective extraction ability.In addition,the polymers can be reused five times effectively without significant loss in performance.Imidacloprid extraction was performed in apple fruit sample by using the prepared magnetic imprinted polymers and was detected with UPLC MS/MS.The molecular imprinting polymers showed good performance in the analysis of spiked apple sample with a linear range of 0.05-1.0 mg L^-1,a limit of detection of 0.048 mg kg^-1,and a limit of quantification of 0.146 mg kg^-1?S/N=3/10?.The recovery percentages of the samples were 77.66-96.57%,and their respective relative standard deviations were 3.36-0.45%.The applicability of the prepared method was compared with the results of previously reported works and higher recovery with smaller RSD value,decreased LOD and LOQ values were noticed.The method also has quick separation ability,high selectivity and a rapid time of one hour.A beta-cyclodextrin based molecular imprinted polymers were prepared using dimethyl sulfoxide as a polymerization medium for selective determination of carbendazim.The polymers consist of a porous and hollow structure,characterized by a scanning electron microscope demonstrating the selective abundant adsorption sites for carbendazim molecule.The selectivity and adsorption capacity of the imprinted polymers were higher than non-imprinted polymers with the maximum adsorption capacity of 3.65 mg g^-1 within 30minutes of total adsorption time.In addition,the reusability of the imprinted polymers was determined to evaluate its effectiveness and stability,which proved that the polymers lost 10%efficiency within seven consecutive recycles.Fungicide carbendazim extraction was performed by using the prepared molecularly imprinted polymers from spiked apple,banana,orange,and peach samples and was detected with UPLC MS/MS.The developed method displayed good linearity over the concentration range of 0.05-2.0 mg L^-1.The recovery percentage of 81.33-97.23 with relative standard deviations of 1.49-4.66%was obtained from spiked apple,banana,orange,and peach samples with a LOD of 0.03 mg kg^-1 and a LOQ of 0.10 mg kg^-1?S/N=3/10?.In comparison with previously reported established methods,this method exhibits higher recovery with lower RSD value,decreased LOD and LOQ values.Besides,the preparation method of the MIPs is quick,easy and cost-effective.The overall performance and results of the proposed methods for both imidacloprid and carbendazim evident that these techniques provided a desirable outcome and is economically feasible,as qualifying the analytical standards and can be used for selective determination of imidacloprid and fungicide carbendazim in varied types of fruit with minimum sample matrix effect,in order to ensure the fruit quality and to promote health safety as a basic concern.