APPLICATION OF HYBRID LINEAR ION TRAP - ORBITRAP MASS SPECTROMETRY FOR THE QUALITATIVE AND QUANTITATIVE ASSESSMENT OF PESTICIDES IN N.W. GREECE

摘要

The extended use of pesticides for agricultural and non-agricultural purposes has resulted in their presence in various environmental matrices. Pesticide residues enter surface water mainly through agricultural run-off. Both parent pesticides and metabolites may exert a toxic action in organisms of freshwater systems, whenever the concentration of a compound is sufficient to trigger such effect. The analysis of pesticide residues in a variety of environmental matrices contributes to ensure their safety and quality. Until recently, multi-residue analysis of such compounds at trace levels has been mainly carried out by means of GC and LC coupled to mass spectrometry. Lately, scientific interest has also been shifted to even more accurate and sensitive detectors. In that direction, the use of high-resolution mass spectrometers (LC-HRMS) and especially Orbitrap technologies enables the acquisition of a theoretically unlimited number of species by means of accurate mass measurements in full-scan mode. This allows obtaining the elemental composition of acquired ions, useful for identification of targeted and untargeted compounds, metabolites, or transformation products [1].In the present study, an SPE sample enrichment procedure was evaluated in order to be applied for the estimation of the pollutant load and its seasonal distribution in natural waters of the Prefecture of Epirus (Aracthos and Louros rivers, Amvrakikos gulf), N.W. Greece. Hybrid LTQ Orbitrap mass spectrometry was employed for the ultra-trace detection and quantification of target pesticides and finally was successfully applied to the analysis of waters. The identification of the positive findings is accomplished with the data from accurate masses of the target ions, based on the full-scan exact mass measurement of [M+H]~+ ions, along with retention time data and characteristic on-source fragment ions. The results obtained confirm that high-resolution mass spectrometry is a helpful and reliable tool for the identification and quantitation of pesticide residues, providing at the same time high accuracy.