Author Archives: Vera

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

July 2019.

López-Ruiz R; Romero-González R; Serra B; Garrido Frenich A

Abstract

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.

Dissipation studies of famoxadone in vegetables under greenhouse conditions using liquid chromatography coupled to high-resolution mass spectrometry: putative elucidation of a new metabolite

September 2019

López-Ruiz R; Romero-González R; Ortega-Carrasco E; Garrido Frenich A

Abstract

Background

Famoxadone is a pesticide that is used to control fungal diseases and its dissipation in vegetables should be monitored. For that purpose, liquid chromatography coupled to mass spectrometry has been used. 

Results

The dissipation of famoxadone has been monitored in cucumber, cherry tomato and courgette under greenhouse conditions at different doses (single and double), using ultra high-performance liquid chromatography coupled to Orbitrap mass spectrometry (Thermo Fisher Scientific, Bremen, Germany). The concentration of famoxadone increased slightly just after the application of the commercial product and then decreased. The half-lives (DT50 ) of famoxadone are different for each matrix, ranging from 2 days (courgette single dose) to 10 days (cucumber double dose). The main metabolites, 4-phenoxybenzoic acid and 1-acetyl-2-phenylhydrazine, were not detected in vegetable samples. Other metabolites described by the European Food and Safety Authority, such as IN-JS940 [(2RS)-2-hydroxy-2-(4-phenoxyphenyl)propanoic acid], IN-KF015 [(5RS)-5-methyl-5-(4-phenoxyphenyl)-1,3-oxazolidine-2,4-dione] and IN-MN467 [(5RS)-5-methyl-3-[(2-nitrophenyl)amino]-5-(4-phenoxyphenyl)-1,3-oxazolidine-2,4-dione], were detected in the three matrices. Untargeted analysis allowed for the putative elucidation of a new metabolite of famoxadone in cucumber (up to 290 μg kg-1 ) and cherry tomato (up to 900 μg kg-1 ) samples.  

Conclusion

The dissipation of famoxadone has been investigated in three vegetables: tomato, cucumber, and courgette. The persistence of famoxadone was low in the three matrices (DT50 less than 10 days). Metabolites of famoxadone were monitored, detecting IN-JS940, IN-MN467 and IN-KF015, and the putative elucidation of a new metabolite of famoxadone was performed by applying software tools. 

Automatic MS Data Analysis to reveal the metabolic pathways of pesticides in fruits and soils

256th ACS National Meeting, Boston, MA (United States of America) 21 August, 2018 

Abstract

In the intensive farming of fruit and vegetable, a variety of pesticides are applied to prevent or eliminate harmful pests from plants. These pesticides can remain in edible parts as residues entering into the food chain. In most of the cases, pesticides can be transformed into metabolites, which are intermediate products of metabolism formed either in plants or animals. The detection of those metabolites does not end in the edible parts of the fruits and vegetables. It is also needed a deep study of soils and water to ensure that the concentration of harmful compounds will not reach the limit stablished by law. Advances in analytical techniques with increased sensitivity have led to the detection of a growing number of metabolites at low concentrations, being HPLC-HRMS the most used analytical method to perform this task. To boost the structure elucidation of the different metabolites, we used MassChemSite 2.0. 

Degradation studies of dimethachlor in soils and water by UHPLC-HRMS: putative elucidation of unknown metabolites

February 2020.

López-Ruiz R; Romero-González R; Ortega-Carrasco E; Martínez Vidal JL; Garrido Frenich A

Abstract

Background

The analytical control of the presence of dimethachlor and its metabolites in environmental samples, such as water and soils, is a main concern. Degradation of this pesticide has been evaluated in two types of soils and two different water conditions at two concentration levels. For that purpose, a new liquid chromatography-mass spectrometry method has been developed and putative identification of new metabolites has been performed. 

Results

An analytical method based on ultra-high-performance liquid chromatography coupled to Orbitrap mass spectrometry (UHPLC-Orbitrap-MS) was developed to monitor the degradation of dimethachlor in environmental samples (water and soils). The degradation of dimethachlor in soils and groundwater samples has been monitored from 1 to 110 days after application of a plant protection product at two doses. Concentration of the parent compound slowly decreased in both matrices. 

DT50 values ranged from 40 to 70 days. Some metabolites were detected in the commercial product and in the samples one day after the application of the plant protection product. In addition, three new metabolites were putatively identified during dimethachlor degradation by untargeted analysis. 

Conclusions

In this study, the degradation of dimethachlor into its metabolites has been studied in soils and water, using a UHPLC-Orbitrap-MS validated method. A putative elucidation of new metabolites of dimethachlor has been carried out applying HRMS and software tools. Degradation results allowed for understanding the behavior of dimethachlor in soils and water and provided information regarding the possible risk of this pesticide and its metabolites to the ecosystem. 

LipostarMSI: Comprehensive, Vendor-Neutral Software for Visualization, Data Analysis, and Automated Molecular Identification in Mass Spectrometry Imaging

January 2020.

Tortorella S, Tiberi P, Bowman AP, Claes BSR, Ščupáková K, Heeren RMA, Ellis SR, Cruciani G. 

Abstract

Mass spectrometry imaging (MSI) visualizes molecular distributions throughout tissues but is blind to dynamic metabolic processes. Here, MSI with high mass resolution together with multiple stable isotope labelling provided spatial analyses of phosphatidylcholine (PC) metabolism in mouse lungs. 

Dysregulated surfactant metabolism is central to many respiratory diseases. Metabolism and turnover of therapeutic pulmonary surfactants were imaged from distributions of intact and metabolic products of an added tracer, universally 13C-labelled dipalmitoyl PC (U13C-DPPC). The parenchymal 

distributions of newly synthesized PC species were also imaged from incorporations of methyl-D9- choline. This dual labelling strategy demonstrated both lack of inhibition of endogenous PC synthesis by exogenous surfactant and location of acyl chain remodeling processes acting on the U13C-DPPClabelled surfactant, leading to formation of polyunsaturated PC lipids. This ability to visualize discrete metabolic events will greatly enhance our understanding of lipid metabolism in diverse tissues and has potential application to both clinical and experimental studies.