Identification of the bound residue composition derived from ~(14)C-labeled chlorsulfuron in soil by using LC-MS and isotope tracing method

摘要

A new method for extracting the bound residue (BR) derived from ~(14)C- labeled chlorsulfuron in soils was developed, and the technique of combining LC- MS with isotope tracing method was subsequently applied to identify the composition of the ~(14)C- BR in a loamy Fluvent derived from marine deposit. The results showed that the ~(14)C-[2-amino-4-methoxyl-6-methyl-1,3,5]-triazine, ~(14)C-[2-amino-4-hydroxy-6-methyl-1,3,5]-triazine and ~(14)C-chlorsulfuron parent compound constituted the main composition of the ~(14)C-BR derived from ~(14)C-labeled chlorsulfuron in the soil. The radioactive ratio of three compounds accounted for 39.8 percent, 35.4 percent and 17.9 percent of total recovered radioactivity, respectively. However, a small amount (3.6 percent of total recovered radioactivity) of the complex of ~(14)C-[2-amino-4-hydroxyl-6-methyl-1,3,5]-triazine might have existed in the ~(14)C-BR in association with an unknown soil substrate. 2-chlorobenzenesulfonamide was also detected to be one of the components of the BR. The results could well explain the mechanism of phytotoxicity caused by the BR derived from chlorsulfuron in soil. In addition, the mechanism of BR formation in soil was also discussed in details.