Research And Application Of Rapid Detection Methods For Organophosphorus Pesticide Residues Based On A Screen-printed Electrode Enzyme Sensor

Organophosphorus pesticides have been widely used in agriculture because of their highly effective insecticidal effect,but their residue is serious in agricultural products due to their large and non-standard use.And the existing detection technologies are not suitable for on-site testing because of time-consuming,laborious and expensive.Acetylcholinesterase(AChE)sensors have been proved to be a convenient and inexpensive method for organophosphorus pesticides residue detection,but they also have some shortcomings,such as poor repeatability,low stability and weak detection signal etc.Therefore,it is very important to develop an excellently sensitive,highly stable and reproducible AChE biosensor.In this paper,three kinds of AChE biosensors were constructed using the screen-printed carbon electrode as the base electrode and signal amplification of nanomaterials in electrochemical biosensors as the mainline to detect the organophosphorus pesticides residue.The main contents include the following three aspects:(1)The preparation and application of an amperometric AChE sensor based on ordered mesoporous carbon-chitosan/ferroferricoxide-chitosan.The ordered mesoporous carbon-chitosan complexes and ferroferric oxide-chitosan complexes were prepared using chitosan with film-forming and adsorbability as the dispersant,and they were used to build an amperometric enzyme sensor for detection of chlorpyrifos,methamidophos and vegetable samples.The recovery rate of methamidophos in vegetables was 95%-103%,and the relative standard deviation was 2.3%-5.3%,so the prepared sensor had good repeatability and stability.(2)The preparation and application of an amperometric AChE sensor based on ordered mesoporous carbon-chitosan/antimony tin oxide-chitosan.The high conductivity of antimony tin oxide could amplify electrochemical signals,and the large surface area of mesoporous carbon could fix more enzymes to improve the sensitivity of sensors.A novel enzyme sensor was constructed using the both advantages and this sensor showed a wide linear range for the detection of chlorpyrifos and methamidophos,which ranged from 0.01 to 105?g/L and from 1 to 600 ?g/L,with a detection limit of 0.01 ?g/L and 1 ?g/L respectively.(3)The preparation and application of an amperometric AChE sensor based on ordered mesoporous carbon-chitosan/cerium oxide-chitosan.Cerium oxide had fastelectron transfer rate and good catalytic performance,and the synergistic effect of cerium oxide and ordered mesoporous carbon was used to construct an enzyme sensor.The performances of this sensor were studied by cyclic voltammetry and differential pulse voltammetry technique.Compared with the above-mentioned two sensors,the amplification effect of the last sensor was the best.The quadratic orthogonal rotation combination test was used to optimize the test conditions based on a single factor test.Under optimal conditions,there existed a good linear correlation between the logarithm of chlorpyrifos / methamidophos concentration and inhibition rate.The linear correlation coefficients were 0.9916 and 0.9937 respectively,and the detection limits were 0.01 ?g/L and 1 ?g/L.Detection results of vegetable samples compared with gas chromatography,the recovery rates of pesticides of both methods were between 90% and 110%,which indicated that the enzyme sensor had a good accuracy.It provided a reliable method for the rapid detection of organophosphorus pesticides residue.