Detection Of Organophosphate Pesticides Based On Immobilized Zr(?) Affinity Chromatography Mechanism

With the development of modern agriculture,pesticides are used in crop cultivation more and more widely to improve the yield and quality of agricultural and sideline products.In last decades,organophosphate pesticides?OPPs?has become the most widely used herbicide and insecticides around the word due to its large variety,high efficacy,wide insecticide range,insecticide diversity and other characteristics.However,it was found that OPPs also have certain toxicity,and some of them are even classified as "highly toxic" by the World Health Organization.Consequently,many countries and organizations have setting maximum residue limits?MRLs?for OPPs in some foods.And it shows a trendency more and more critical.Hence,developing fast,sensitive and accurate detection method of OPPs is of great importance in order to achieving the monitoring of trace OPPs in different environments and systems,e.g.crops,water,soils.In this thesis,one Zr???modified solid phase extraction?SPE?material and two novel Zr???functionalized chemical modified electrodes were prepared for OPPs analysing based on immobilized metal affinity chromatography?IMAC?mechanism.?1?Fe₃O₄-ethylenediamine tetraacetic acid?EDTA?@Zr???nanocomposites were prepared firstly with ?one-pot? method;and then a layer of Zr???was fabricated utilizing the strong chelating interaction between EDTA and Zr???.Multi-analytic methods were used to characterize the resulted nanoparticles including transmission electron microscope?TEM?,energy dispersive spectrdmeter?EDS?,and fourier transform infrared spectoscopy?FT-IR?.SPE conditions were optimized using four typical OPPs fenitrothion fenthion chlorpyrifos methidathion.Coupling with GC-MS,limits of detection?LOD?for target OPPs were in the range of 0.10-10.30 ng mL^-1 with relative standard deviations?RSDs?of 0.61-4.40%?n=3?.Linear ranges were over three orders of magnitudes?correlation coefficients,R2 > 0.9995?.The Fe₃O₄-EDTA@Zr???was successfully applied to extract OPPs from two real water samples with recoveries of 86.95-112.6%?RSDs 1.20-10.4%,n=3?.?2?One novel enzyme-free electrochemical sensor was fabricated for direct determination of p-nitrophenyl-substituted organophosphate pesticides?PNP-OPPs?.Zr???functionized glassy carbon electrode?GCE?was prepared through two chemcial reaction to derive one layer of phosphoric group on the surface of GCE firstly,and then a layer of Zr???was fabricated via self-assembly monolayers?SAMs?technique.Multi-analytic methods were used to characterize the resulted electrode including TEM,EDS,and FT-IR.Conditions of enriching steps and square wave voltammetry were optimized using parathion as the model.Utilizing the special interaction between Zr???and phosphonate moiety,the sensor exhibited high sensitivity and selectivity to PNP-OPPs.Under optimum conditions,recoveries of parathion were in the range of 99.30-102.2% with RSDs of 0.45-0.72%?n=3?at three spiked levels.Linear range was 1.0-80.0 ng m L^-1?ppb?with a detection limit?LOD?of 0.25 ng mL^-1?signal/niose?S/N?=3?.The electrode was successfully used to detect parathion in pear samples,recoveries were 94.67-102.0%?RSDs,2.11-3.03%,n=3?.Moreover,the detection mechanism of parathion was studied based on the relationship between reduction potential and pH.?3?11-Mercaptoundecylphosphoric acid?MDPA?was used as bridge to immobilize Zr???on the surface of Au electrode via SAMs technique making full use of chelations between thiol and Au,as well as Zr???and phosphoric group.By this way,the synthetic steps was largely decreased.Multi-analytic methods were used to characterize the resulted eletrode including TEM,EDS,and FT-IR.The enriching performance and electrochemical behavior were investigated.Under the optimum conditions,recoveries of parathion were in the range of 99.67-100.4% with RSDs of 0.15-0.85%?n=3?at three spiked levels by square wave voltammetry.Linear range was 1.0-60.0 ng m L^-1?R2>0.9939?with LOD of 0.2 ng mL^-1?S/N=3?.The electrode was successfully used to detect parathion in environmental water?jinghu water and tap water?,Chinese cabbage and pear samples with recoveries of 98.44%-105.5% and RSDs of 0.62-3.06%?n=3?.