Identification of Dufulin photolysis and hydrolysis products in water using a 13C stable isotope assisted HPLC-HRMS strategy

•Dufulin degrades more readily under acidic and alkaline conditions.•Using 13C labeling of Dufulin and targeted and non-targeted methods, six transformation products were identified.•Five transformation products were confirmed through corresponding reference standards.•Two transformation products reached concentrations equivalent to 27 % and 9.8 % of the initial Dufulin concentration.•Two transformation products could pose a higher ecotoxicological risk than Dufulin. Dufulin is an efficient antiviral agent for plants, however, data on its environmental fate, particularly concerning its transformation products (TPs), remain scarce. The TPs formed during abiotic degradation may pose significant environmental risks due to potential toxicity. Therefore, this study systematically investigated the hydrolysis and photolysis kinetics of Dufulin in aqueous solutions across various pH conditions. By employing HPLC-HRMS and 13C stable isotope labeling, we identified and quantified Dufulin and its degradation products. The results indicated that Dufulin undergoes accelerated photolysis under both acidic and alkaline conditions, while hydrolysis, although less influenced by pH, was comparatively slower than photolysis. Six TPs were identified and confirmed, five of which were reported for the first time. Moreover, abiotic transformation pathways of Dufulin in water were proposed. Predictions by the ECOSAR software indicated that the toxicity of two of the identified TPs was higher than that of the parent compound, meriting further assessment. These findings provide crucial insights into the environmental risks associated with Dufulin and underscore the scientific validity of using HPLC-HRMS combined with 13C stable isotope labeling for TP identification. [Display omitted]