Filtern
Dokumenttyp
- Posterpräsentation (2)
- Vortrag (1)
Referierte Publikation
- nein (3)
Schlagworte
- Pesticides (3) (entfernen)
Eingeladener Vortrag
- nein (1)
Among major food contaminants agrochemicals (including insecticides, fungicides and herbicides) are a threat for food safety in many countries. Once they entered the food chain or the environment, the parent compound can be transformed into different products by manmade and natural processes. The transformation products (TPs) might be more toxic and stable than the parent compound. In addition to this the transformation products might undergo conjugation with different compounds and/or changed to phase II metabolites.
Conventional in-vivo or in-vitro methods to study phase I and II metabolism have drawbacks of long-time sample preparation and matrix complexity. Online coupling of an electrochemical cell with liquid chromatography-mass spectrometry (EC–LC–MS) is a promising technique to study metabolites, fate and transformation products of pesticides. The new approach enables to identify metabolic transformation products by oxidizing analyte of interest on the EC, separate the metabolites on HPLC and identifying them by MS.
The aim of the present study is to identify/mimic pesticides phase I metabolites using electrochemical cell coupled to liquid chromatography-mass spectrometry (EC-LC-MS). Metabolic transformed products of two model compounds, fluopyram (fungicide) and chlorpyrifos (insecticide) were studied by EC upfront with MS. The results of EC-LC-MS are compared and discussed with those derived from in-vitro assays and the metabolites identified by LC-MS/MS.
Metabolic transformation products of pesticides by electrochemical cell coupled to LC-MS (EC-LC-MS)
(2016)
Metabolic transformation products (TPs) of the insecticide chlorpyrifos (CPF), the new fungicide fluopyram (FLP) and the broad-spectrum herbicide, glyphosate (GLP), were studied by electrochemistry coupled to mass spectrometry (EC-MS) for the first time. Phase I metabolites of the three pesticides from rat liver in-vitro assay experiments were studied by LC-MS/MS and compared to electrochemically oxidized products from EC-MS.
Known metabolites from S-oxidation, O-dealkylation and hydroxylation of the insecticide chlorpyrifos have been identified by EC-MS and simulated to in-vitro assays. Chlorpyrifos-oxon (CPF-oxon), diethylthiophosphate (DETP), 3,5,6-trichloropiridinol (TCP), diethylphosphate (DEP) and 2,3,5-trichloropyridine (TCPy) were the main EC oxidative TPs and in-vitro assay metabolites of CPF which was also reported by Choe et al.. Fluopyram was extensively converted to a number of electrochemical products including mono- and dihydroxylated derivatives and yet unidentified TPs. Rat liver microsomal assay experiments showed mainly hydroxylated metabolites of FLP which was also reported by the European Food Safety Agency (EFSA). Aminomethyl phosphonic acid (AMPA) was the main TP of glyphosate detected from both EC-MS analysis and in-vitro assay tests.
A number of TPs of CPF, FLP and GLP have been identified by electrochemistry online mass spectrometry and compared to in-vitro assays. Using electrochemistry upfront MS enables fast and matrix free prediction of metabolic pathways, transformation products and/or fate of pesticides. Further studies will focus on structural characterization of detected compounds, phase II metabolites and investigation of real samples.
Within a class of agrochemical residues, pesticides are significant concern due to their various adverse effects on people, animals and the environmental systems. Once they entered to food or to the environment, the parent compound is transformed to metabolites which have different toxicity profiles. Activities like food cooking and waste water treatment (WWT) may lead to produce more toxic metabolites than the parent substances.
Online coupling of electrochemistry with liquid chromatography mass spectrometry (EC-HPLC-MS) is one of the most promising and powerful techniques for metabolite studies which exploited widely for pharmaceuticals so far [1]. However, data on the application of EC-HPLC-MS to simulate environmental transformation products, the fate of contaminants and their metabolic pathways are rare. The oxidation of analyte of interest on the EC, separate the metabolites on HPLC and identifying them by MS gives enormous advantages to identify the contaminants transformation products [2]. Thus, applying this technique (EC-MS, EC-HPLC-MS, and HPLC-EC-MS) for transformation products of pesticide residues is urgently needed.
The main interest of this study will be investigating the electrochemical oxidative degradation products, simulating to in-vitro metabolites and transformation processes of selected pesticides in food and environmental samples. The parent pesticides’, like carbamates and abamectin, oxidation by EC, product metabolites identification and their fates will be discussed using electrochemistry coupled to HPLC-MS techniques.