Study On Determination Of Carfentrazone-ethyl Residue In Wheat And Soil And Its Adsorption Properties To Soil

Carfentrazone-ethyl is a widely used herbicide.In this paper,an analysis method for the determination of carfentrazone-ethyl residues in wheat plants,grain and soil samples was established,and the adsorption behavior and the influencing factors of carfentrazone-ethyl in three different soils was studied,which has guiding significance for the comprehensive and accurate evaluation of its ecological environment behaviors.The main results are as follow:(1)Through screening and comparison for the pretreatment method,it was determined that elution was carried out with a mixture of n-hexane and acetone(volume ratio 6:4),dispersant PSA was added,and graphitized carbon GCB was used for purification to optimize the analysis conditions of gas chromatographic instrument and establish a method for residue analysis of carfentrazone-ethyl in wheat plants,kernels and soil by the ECD detector.The spike recovery experiments showed that the average recovery rate of wheat plants were 99.0% to 116.2%,and the RSD were 1.8% to 3.6%,and the average grain recovery were 95.9% to 115.4%,and the RSD were 1.8% to 3.6%.and the average recovery rate of soil were 96.3% to 104.5%,and the RSD were 2.7% to 6.8%.The lowest detection concentration of wheat plants,grain and soil were 0.05mg/kg.This method has the advantages of good reproducibility,high recovery,simple operation,which meets the analysis requirements of pesticide residue.(2)Recovery experiments on carfentrazone-ethyl in water samples showed that when the concentration of carfentrazone-ethyl were 0.5,1.0 and 5.0mg/L respectively,the recoveries were 90.8% to 101.6%,and the RSDs were 0.7% to 3.4%.The minimum detectable concentration was 0.5mg/L,which meets the analysis requirements of the study on the adsorption characteristics.(3)The adsorption of carfentrazone-ethyl in three different soils followed the pseudo-second-order kinetic model and thecorrelation coefficient were between 0.998 and 0.9999,and the equilibrium time of adsorption was 12 h.The light clay from Chongqing in the three test soils had the strongest adsorption capacity for carfentrazone-ethyl.(4)The adsorption capacity of carfentrazone-ethyl by soil increased with the increase of soil organic matter.The best adsorption effect of carfentrazone-ethyl in soil can be obtained when pH was 6.4.When the pH was alkaline,the hydrolysis reaction occurred and the adsorption capacity decreased.Within the measure concentration range,the adsorption capacity of the test soil from Hefei increased with the increase of the concentration of cetyltrimethylammonium bromide cationic surfactant(CTAB,while the adsorption capacity of carfentrazone-ethyl decreased with increasing of the concentration of Triton X-100 anionic surfactant(TX-100).