Dissipation behavior and residue distribution of fluazaindolizine and its seven metabolites in tomato ecosystem based on SAX SPE procedure using HPLC-QqQ-MS/MS technique.

Fluazaindolizine suspension concentrate (500gL-1 SC), as a pre-commercialized product, was firstly investigated under open-field conditions. A sensitive method for simultaneous determination of fluazaindolizine and seven metabolites (IN-QEK31, IN-F4106, IN-A5760, IN-UJV12, IN-UNS90, IN-QZY47 and IN-TMQ01) was established and validated using HPLC-QqQ-MS/MS technique. The LOQs of these pollutants in tomato were 0.01mgkg-1, and their recoveries were 81.1%-117% with the relative standard deviations (RSDs <11.8%). The dissipation behaviours of fluazaindolizine in soil followed first-order kinetics with the half lives of 4.6-32.4days, whilst the residues in plant were below its LOQ after 7days. The fluazaindolizine residues in soil were below 0.963mgkg-1, based on root irrigation applications (50-75mg a.i. per plant) twice and pre-harvest interval (PHI, 3days), while the residues of IN-QEK31, IN-F4106 and IN-A5760 were below 3.9mgkg-1, excluding other four metabolites (<0.01mgkg-1). The residues of fluazaindolizine in tomato were below 0.01mgkg-1, and IN-QEK31 remained 0.135mgkg-1. The current study could not only guide reasonable usage of the formulation, but also facilitate the setting of residue definition and its maximum residue limits (MRLs) of fluazaindolizine in tomato.