Recently, the Innovation Team for Risk Control of Pesticide Application at the Institute of Plant Protection, Chinese Academy of Agricultural Sciences (IPPCAAS) has successfully elucidated the transformation pathways and environmental risks of the domestically developed pesticide Dufulin in aquatic environments. Using ¹³C stable isotope labeling coupled with High-Resolution Mass Spectrum (HRMS), the team identified the major transformation products (TPs) of Dufulin and assessed their potential ecotoxicity using the ECOSAR model. The findings, published in the top environmental journal  Water Research , provide crucial insights into pesticide degradation mechanisms, unknown TPs identification, and environmental risk assessment.

Dufulin, an efficient antiviral agent for plants, has been widely used in agricultural production. However, its environmental fate, particularly the formation and non-target toxicity of TPs, remains unclear. In aquatic environments, Dufulin undergoes abiotic degaradation, generating TPs that may pose greater ecological risks than the parent compound. Therefore, it is critical to investigate the environmental behaviour of Dufulin and the identification and risk evaluation of corresponding TPs.

This study investigated the degradation behaviour of Dufulin in aquatic environments and described its photolysis and hydrolysis processes using different kinetic models. The Ultra-High Performance Liquid Chromatography-Quadrupole-Orbitrap Mass Spectrometry (UHPLC-Q-Exactive-MS) coupled with ¹³C stable isotope labeling was utilized to comprehensively identify and quantify Dufulin and its TPs for the first time. A total of six TPs were identified and confirmed, among which five were newly discovered. It further proposed that the main non-biological pathways of Dufulin in water include reductive cleavage, oxidation, elimination, and deethylation, which provided theoretical support for a deeper understanding of its environmental fate. Additionally, the ECOSAR model assessment revealed that two of these TPs may exhibit higher ecological toxicity to zebrafish, Daphnia magna, and green algae might be higher than that of the parent compound. This finding holds significant implications for the environmental risk assessment of Dufulin.

This research has made a breakthrough in the methodology for screening and identifying unknown TPs of pesticides using ¹³C stable isotope labeling. This approach enables structural confirmation of potential transformation products without the need for standard comparison, effectively solving the problem of pesticide TPs identification. It significantly enhances the efficiency of unknown compound identification and provides a valuable reference for the identification and toxicity risk assessment of other pesticide TPs.

IPPCAAS is the leading institution of this study. Dr. Yu Bochi is the first author, and Professor Liu Xiangang is the corresponding author. This study was supported by the International (Regional) Cooperation and Exchange (ICE) Projects of the National Natural Science Foundation of China (Grant No.32261133527).

Source: Institute of Plant Protection