Detection Of Pesticide Residues Based On Porous Organic Polymers And Biochar Materials

Phenylurea pesticides and amide pesticides are widely used due to their high efficiency,low toxicity and wide range of action.However,it will be enriched in the environment and eventually enter the human body,which will affect human life and health.In recent years,porous organic polymer materials have shown great splendor in adsorption due to their high specific surface area,high porosity and structural controllability.At the same time biochar materials are also closely followed because of their simple synthesis,easy availability and rich oxygen-containing functional groups.Therefore,these two materials are used for pesticide detection.In this paper,silicon spheres and magnetic silicon spheres were aminated by silane coupling agent EEDTS to synthesize carboxyl-functionalized porous organic polymers（CPOP）and carboxyl-functionalized magnetic porous organic polymers（CMPOP）.At the same time,the obtained walnut green skin was carbonized at high temperature to obtain original biochar（OBC）,and the walnut green skin was modified to obtain walnut green husk-sepiolite composite biochar（SBC）,walnut green husk-iron trichloride composite biochar（MBC）,walnut green husk-sepiolite-iron trichloride composite biochar（SMBC）.The materials were analyzed by SEM,FT-IR,XRD,nitrogen adsorption and thermogravimetric analysis,which proved that the materials were successfully synthesized.Through adsorption experiments,it was found that the adsorption process of these materials conformed to Langmuir isotherm model and pseudo-second-order kinetic model.Meanwhile,HPLC detection methods for phenylurea herbicides and amide herbicides were established.Under the optimized experimental conditions,five HPLC detection methods obtained a good linear range,R²>0.9900.At the same time,the LOD value was obtained when the S/N was 3,and the LOQ value was obtained when the S/N was 10.Among them,five PUHs were detected by CPOP-HPLC method and CMPOP-HPLC method,the LOD values measured by the two methods were 0.3-0.6 ng mL^-1 and 0.09-0.17 ng mL^-1,and the LOQ values were 0.07-0.22 ng mL^-1 and 0.029-0.56 ng mL^-1,the RSD were 1.5-5.1%and 0.62-4.05%,respectively.The standard addition recovery experiments were carried out on cucumber,apple and cabbage,and the recovery rates were 96.97-108.28%and 103.76-118.34%,respectively.Three amide herbicides were detected by SBC-HPLC,MBC-HPLC and SMBC-HPLC,and lower LOD,LOQ and higher recovery were obtained.The LOD values measured by the three methods were 0.004-0.085 ng mL^-1,0.003-0.012 ng mL^-1 and 0.013-0.025 ng mL^-1,respectively.The LOQ values were 0.013-0.282 ng mL^-1,0.009-0.039 ng mL^-1 and 0.045-0.082 ng mL^-1,respectively.The relative standard deviations were 0.56-2.03%,1.43-1.68%and 2.30-3.86%,respectively.The recovery rates of tomato,pear and cabbage were 80.92-115.35%,80.05-87.76%and 82.46-98.9%,respectively.