Investigação da persistência do endosulfan e seus metabólitos após desastre ambiental utilizando GCxGC/TOFMS

Abstract

In 2008, an environmental disaster occurred with the leakage of around 8,000 liters of the pesticide endosulfan, which caused a wide-ranging impact on the Paraíba do Sul River, one of the most important rivers in the southeastern region of Brazil. However, no studies were found to assess the persistence of endosulfan and its metabolites in this environment. Organochlorine pesticides, including endosulfan, are the most toxic group of pesticides that are directly related to acute poisoning and can remain in the environment for many years. Comprehensive two-dimensional gas chromatography coupled with time-of-flight mass spectrometry (GC×GC/TOFMS) is a powerful tool for analyzing pesticide residues and their metabolites. The objective of the research was to develop a methodology for the quantification of endosulfan and its metabolites, among other organochlorine pesticides, with simultaneous analysis of non-target compounds in water and sediment and to evaluate the persistence of these compounds in the region impacted by the 2008 environmental accident. The sample extraction methods validated in this study employed Solid Phase Extraction (SPE) for water samples and QuEChERS for sediment sample extraction. The method was developed with a focus on fast chromatography for the determination of the analytes tetrachloro-m-xylene, α-BHC, β-BHC, δ-BHC, γ-BHC, heptachlor, aldrin, heptachlor epoxide, trans-chlordane, α-endosulfan , chlordane, dieldrin, 4.4 DDE, endrin, β-endosulfan, 4.4 DDD, endrin aldehyde, 4.4 DDT, endosulfan sulfate, endrin ketone, methoxychlor and decachlorobiphenyl, and the validation process followed ANVISA criteria. The total time of chromatographic analysis was 12 minutes. The recovery results were between 70.0 to 117.4% for water samples and 71.3 to 118.5% for sediment extraction, validating 15 and 19 analytes of 25 compounds, respectively in each method. The method was validated at all stages with statistical analysis in RStudio. The detection limits range from 0.38 to 173.74 ng mL-1 and quantification ranges from 1.18 and 526.49 ng mL-1. Water samples and sediment samples (n=16) were studied, collected in a rainy and a in a dry season. The quantitative results obtained determined the presence of endosulfan lactone in the Pirapetinga River, below the railway and on the banks of the Presidente Dutra highway, at concentrations of 142 and 255 ng mL-1, respectively, while for β-BHC at the mouth of the Pirapetinga river the concentration was 40,7 ng mL-1. The detection of the isomer product of endosulfan degradation and the absence of the α and β isomers of endosulfan indicate an old contamination. Analysis of 184 non-target compounds tentatively identified drugs, miscellaneous chemicals, and other pesticides present throughout the study area. It is concluded that the developed method is effective for the analysis of organochlorine compounds and other tentatively found compounds, warning about the current quality of water resources.