Dissipation dynamics and final residues of cloransulam-methyl in soybean and soil

Abstract

This work is the first report on the dissipation and final residue of cloransulam-methyl on soybean plant at field conditions. A fast, simple, and reliable residue analytical method for determination of cloransulam-methyl in soybean matrices and soil was developed based on quick, easy, cheap, effective, rugged, and safe (QuEChERS) sample preparation and liquid chromatography-tandem mass spectrometry (LC-MS/MS) detection. The average recoveries of cloransulam-methyl in soybean matrices and soil ranged from 80 to 105%, with RSDs between 3-11%. The limit of detection (LOD) was 0.001 mg kg(-1) for soybean grain, plant, and soil and was 0.005 mg kg(-1) for soybean straw. This method was then used to characterize dissipation of cloransulam-methyl in soybeans and soil from three locations in China for the first time. Cloransulam-methyl dissipated quickly in soybean plant with half-lives (T1/2) of 0.21-0.56 days. The dissipation dynamic in soil was characterized using both first-order kinetics model and two-compartment model, and the half-lives were similar, ranging from 0.44 to 5.53 days at three experimental sites in 2012 and 2013. The final residue data showed a very low level of cloransulam-methyl in soil (≤0.026 mg kg(-1)), soybean grain (≤0.001 mg kg(-1)), and straw (≤0.005 mg kg(-1)) samples at harvest time. With the faster and simple analytical method on soybean and soil, rapid dissipation of cloransulam-methyl was observed at three geospatial locations in China, and the terminal residue levels were negligible, so mammalian ingestion exposure is minimal.