BONANSEA ROCIO
Congresos y reuniones científicas
Título:
Analysis of pesticides in water samples based on the combination of solid phase extraction and solid phase microextraction coupled to gas chromatography mass detection.
Autor/es:
BONANSEA, R.; WUNDERLIN,D.A.; AMÉ, M.V.
Lugar:
Berlin
Reunión:
Congreso; 6th Setac World Congress Europe 22nd Annual Meeting of the society of environmental toxicology and Chemistry; 2012
Resumen:
The increase of the agricultural surface area in Argentina has triggered the generalized use of pesticides, which are spread across soils contaminating both surface and ground-waters. The aim of this study was: (a) develop a sensitive Gas Chromatography tandem Mass Spectrometry (GC?MS) method for the quantification of the most widely used pesticides at environmentally relevant concentrations and (b) test this method with surface waters collected from the Suquía River basin, Córdoba, Argentina.
Sample pretreatment involves a combination of Solid Phase Extraction (SPE) and Solid Phase Microextraction (SPME) affording highly effective enrichment of six pesticides, which can be analyzed at ppb levels. We tested the effect of SPE cartridges, elution solvents as well as SPME fiber, absorption-desorption temperature and time, head-space or immersion. A fractional factorial design was applied to obtain optimal conditions. GC and MS operational issues were also optimized to afford LODs in the same range that ECD detectors. The optimized method was validated in terms of linearity, precision, recovery and repeatability, showing that the proposed procedure is sensitive (LODs ranging 0.2 to 3.5 ng L-1), precise and robust (recoveries ranged 61 - 104%, RSD varied from 4.0% to 22.6 %), with a linear analytical range from 0.1 to 10 ug L-1.
This method was successfully applied to natural water samples, collected at five monitoring sites along Suquía River, considering pre and post-application of agricultural pesticides. Most studied pesticides were present throughout the entire period. Nevertheless, post-application period showed concentrations of atrazine, acetochlor, endosulfan, endosulfan sulfate and cypermethrine 1.5 to 5 fold higher than the corresponding to pre-application. As expected, highest levels of pesticides were observed in areas with intensive agricultural practices, being atrazine, cypermetrine and endosulfan sulfate predominant. In urban or recreational areas the prevalent pesticide was cypermethrine. Some values surpasse the National Guidelines for pesticides in freshwaters, pointing out the need of controls in addition to the evaluation of damage to aquatic biota.
Sample pretreatment involves a combination of Solid Phase Extraction (SPE) and Solid Phase Microextraction (SPME) affording highly effective enrichment of six pesticides, which can be analyzed at ppb levels. We tested the effect of SPE cartridges, elution solvents as well as SPME fiber, absorption-desorption temperature and time, head-space or immersion. A fractional factorial design was applied to obtain optimal conditions. GC and MS operational issues were also optimized to afford LODs in the same range that ECD detectors. The optimized method was validated in terms of linearity, precision, recovery and repeatability, showing that the proposed procedure is sensitive (LODs ranging 0.2 to 3.5 ng L-1), precise and robust (recoveries ranged 61 - 104%, RSD varied from 4.0% to 22.6 %), with a linear analytical range from 0.1 to 10 ug L-1.
This method was successfully applied to natural water samples, collected at five monitoring sites along Suquía River, considering pre and post-application of agricultural pesticides. Most studied pesticides were present throughout the entire period. Nevertheless, post-application period showed concentrations of atrazine, acetochlor, endosulfan, endosulfan sulfate and cypermethrine 1.5 to 5 fold higher than the corresponding to pre-application. As expected, highest levels of pesticides were observed in areas with intensive agricultural practices, being atrazine, cypermetrine and endosulfan sulfate predominant. In urban or recreational areas the prevalent pesticide was cypermethrine. Some values surpasse the National Guidelines for pesticides in freshwaters, pointing out the need of controls in addition to the evaluation of damage to aquatic biota.
