Dissipation kinetic studies of fenamidone and propamocarb in vegetables under greenhouse conditions using liquid and gas chromatography coupled to high-resolution mass spectrometry

• Published in: Chemosphere (Oxford) 2019-07, Vol.226, p.36-46
• Main Authors: López-Ruiz, Rosalía, Romero-González, Roberto, Serra, Blanca, Garrido Frenich, Antonia
• Format: Article
• Language: English
• Subjects: Fenamidone; GC-HRMS; LC-HRMS; Metabolites; Propamocarb; Unknown analysis
• ISSN: 0045-6535; 1879-1298
• DOI: 10.1016/j.chemosphere.2019.03.118

In this study, fenamidone, propamocarb and their transformation products were monitored in cherry tomato, cucumber, and courgette samples. A mixture of both compounds, which have different physico-chemical characteristics, are commercially available (Consento®). For analysis, ultra high-performance liquid chromatography coupled to Orbitrap mass spectrometry (UHPLC-Orbitrap-MS) and gas chromatography coupled to Q-Orbitrap mass spectrometry (GC-Q-Orbitrap-MS) were used. The dissipation of these active ingredients was monitored at two doses (normal and double dose) from 1 to 40 days after the application of the commercial product. Half-lives (DT50) were lower than 30 days for both compounds, which indicates low persistence. Metabolites of both compounds were also monitored due to in some cases these can be more dangerous for human health than the parent compounds. The metabolites monitored were RPA 410193 ((5S)-3-anilino-5-methyl-5-phenylimidazolidine-2,4-dione), acetophenone, 2-phenylpropionic acid, 5-methyl-5-phenylhydantoin and 5-methylhydantoin for fenamidone, and propamocarb hydrochloride (propyl 3-(dimethylamino)propylcarbamate hydrochloride), N-oxide propamocarb (propyl [3-(dimethylnitroryl)propyl]carbamate), oxazoline-2-one propamocarb (3-[3-(dimethylamino)propyl]-4-hydroxy-4-methyl-1,3-oxazolidin-2-one), 2-hydroxypropamocarb and n-desmethyl propamocarb (propyl [3-(methylamino)propyl]carbamate) for propamocarb. In addition, they were detected one day after the application of commercial product, being RPA 410193, the metabolite detected at the highest concentration in samples. Retrospective analysis of incurred samples allowed putative identification of four possible new metabolites of propamocarb and one of fenamidone. [Display omitted] •HRMS was used to study the degradation of fenamidone and propamocarb in vegetables.•Degradation in tomato, cucumber and courgette under greenhouse conditions.•Persistence of the compounds was low, with DT50 values lower than 35 days.•Known and unknown metabolites were detected in the incurred samples.•Five new metabolites were putative elucidated applying several software tools.