Determination Of Organophosphrous Pesticide Residues Based On Nanoenzyme

With the increasing proportion of organophosphorus pesticides in agricultural production,the problem of pesticide residues is becoming more and more serious.Organophosphorus pesticide is a kind of neurotoxin,which can react with acetylcholinesterase in vivo to inactivate it,leading to the excessive accumulation of acetylcholine as a cholinergic receptor site,which makes the cholinergic nerve in an exciting state for a long time and causes irreversible effects on the central nervous system and peripheral nervous system of the body,thus damaging the health of the body.This mechanism has been widely used in the construction of pesticide detection sensors.Nano-enzymes are a new generation of artificial enzymes.They not only have the unique properties of nanomaterials,but also have the catalytic ability of natural enzymes.Cerium nanomaterials have many kinds of enzymatic activities because of the interaction between Ce3+and Ce4+,which attracts more and more attention.In this study,a simple two-phase coordination method was used to synthesize cerium nanomaterials with enzymatic activity.With mainly rare earth metal cerium and aspartic acid synthesized by organic-inorganic two-phase coordination under alkaline conditions.The enzymatic activity of cerium nanomaterials was optimized by improving the ratio of cerium ions to aspartic acid,the reaction solvent needed for coordination reaction and the optical rotation of aspartic acid.The results showed that when the ratio of cerium ion to L-aspartic acid was 1:3,the activity of cerium-like oxidase synthesized from L-aspartic acid dissolved in absolute ethanol was the best.In this study,the oxidase-like activity of synthesized cerium nanomaterials was used to catalyze the reaction of organic substrate TMB to change its color,so that the corresponding ultraviolet absorption value at 650 nm changed.The choline produced by the reaction of acetylcholinesterase and acetylcholine could inhibit the oxidation of TMB,thus inhibiting its color changing.Organophosphorus pesticides could inhibit the activity of acetylcholinesterase.The inactivation of acetylcholinesterase reduced the production of choline,thus reducing the inhibition of TMB oxidation reaction.The TMB color would also show linear changes with the concentration of organophosphorus pesticides,and the corresponding UV absorption value at 650 nm would also show linear changes,so as to detect organophosphorus pesticide residues.Finally,a fast colorimetric detection of organophosphorus pesticide dichlorvos was achieved in the range of 0.5-500 ?g/L.The minimum detection concentration could be 0.5?g/L.This study could realize the rapid detection of organophosphorus pesticide dichlorvos within 10 minutes,the detection minimum concentration could reach 0.5 ?g/L.The detection sensitivity is higher than the detection limit of 0.2 mg/kg in the national standard,and the detection cost is low.The method involved in this study was applied to the detection of real samples,the recovery range was 83.98%-104.26%,which proved the practicability of this experiment.Correlation analysis with GC-MS method was carried out and showed that the correlation coefficient was 0.996,which was significantly correlative.The results showed that this method could accurately detect organophosphorus pesticide residues.