Effect of humic acids,nitrate and oxygen on the photodegradation of the flubendiamide insecticide: identification of products

Flubendiamide is a ryanodine insecticide that shows a strong insecticidal activity and is relatively safe for non-target organisms. Actually only flubendiamide and its product desiodo-flubendiamide have been studied during catalytic degradation using TiO₂ and ZnO. Therefore, here we tested the photocatalytic removal of flubendiamide in the presence of nitrates or humic acids. Degradation kinetics were monitored using high-performance liquid chromatography ultraviolet–visible detector. Product identification was done using a high-resolution time-of-flight mass spectrometer coupled to a gas chromatograph (GC-HRMS). Results show that the addition of humic acids at 10 mg l^?1 increased the removal of flubendiamide more than five times. The addition of nitrate ions at 10 mg l^?1 had no influence. The removal of flubendiamide was more than ten times faster in experiments with oxygen purging. Fourteen degradation products were identified, which can be classified into three groups: phthalimide and related phthalic acid derivatives, fluorinated species related to the second amide moiety, and advanced transformation products.