EXTRACTION OF PERSISTENT ORGANOCHLORINE POLLUTANTS IN REMAINING FRAGMENTS OF MATA ATLÂNTICA, RJ: COMPARISON OF METHODS.

Persistent Organic Pollutants (POPs) are toxic substances of natural and anthropic origin that are ubiquitous pollutants in all environmental compartiments (soils, waters, air and biota). POPs have long half-lives in soils, sediments, air or biota and are hydrophobic and lipophilic. These characteristics confer persistence on the chemicals in biota, which accumulate a nd magnify in foodchains. POPs are normally stable and have the propensity to form a gas under appropriate environmental temperatures. Hence, they may volatilise from soil and contamined areas into the atmosphere. Because of their resistence to breakdown reactions in air, they can travel long distances (are subject to long-range atmospheric transport) before being re-deposited. Therefore, could acummulate in an area far removed from where they use or emmited. The Brazilian Environmental Legislation is still incipient regarding monitoring measures of the contamination and soil management. In this way, the main aim of this work was to perform a preliminary study to investigate the presence of the persistent organochlorine pollutants a and ß - HCH, lindane (?- HCH), alaclor, heptaclor, metolaclor, aldrin, endrin, dieldrin, a and ß endosulfan, DDT and isomers, in soils of remaining fragments of Mata Atlântica in the National Park of Serra dos Órgãos and in the region of Córrego Sujo catchment basins, tributary of Rio Preto. It was performed the extracion of POPs from soils using Soxhlet aparatus, ultrasound and microwave radiation energy, following by a cleanup step (C18 and/or Florisil) to eliminate matrix interferences, and further analysis by gas chromatography equipped with electon-capture detection (ECD) for identification and quantification of the POPs. The developed method for the determination of persistent organochlorine pollutants in soils was based in US-EPA recommended procedures and validated according to INMETRO instructions. It was obtained the detection and quantification limits for the instrument and method for the different soils matrix and extraction methodologies. Recoveries results obtained from spiked samples employing soxhlet, ultrasound and microowave assisted extraction methods showed values between 70 and 130 %, considered acceptable for trace analysis in environmental samples. It could be observed for some of the analyte recoveries values higher than 130 %, which can be related to matrix contribution, due to high organic carbon contents (8- 17 %). It was also performed a recovery study in certified reference material (ERM®- CC007) that showed good results. It was verified higher recoveries results when the microwave assisted extraction technique was used. In order to confirm the presence of analytes of interest in the analysed samples the exchange of estacionary phase was carried out. The obtained results showed low concentration of organochlorine compounds in the soils sampled in the studied areas. It could be concluded that this area is not considered of environmental concern.Coordenação de Aperfeiçoamento de Pessoal de Nível SuperiorEXTRAÇÃO DE POLUENTES ORGANOCLORADOS PERSISTENTES EM FRAGMENTOS REMANESCENTES DA MATA ATLÂNTICA, RJ: COMPARAÇÃO DE MÉTODOS. Poluentes orgânicos persistentes (POPs) são substâncias geradas por processos naturais e antrópicos que são encontrados em todos os compartimentos ambientais (solo, água, ar e biota). Os POPs tem meia-vida prolongada, são lipofílicos e hidrofóbicos. Essas características fazem com que esses compostos se acumulem e se magnifiquem na cadeia trófica. Os POPs são normalmente estáveis a degradação, mas podem volatilizar de solos e áreas contaminadas sob condições ambientais favoráveis. Devido a este fato, estão sujeitos ao transporte à longa distância, antes de serem novamente re-depositados. Conseqüentemente, podem acumular-se em áreas bem distantes de onde foram inicialmente usados ou emitidos. A Legislação Ambiental Brasileira ainda é bastante incipiente com relação às medidas de monitoramento da contaminação e gestão de solos. Apenas normas para disposição de resíduos estão disponíveis. Neste sentido, o trabalho desenvolvido teve por objetivo realizar um estudo preliminar sobre a presença dos poluentes organoclorados persistentes a e ß - HCH, lindano (?- HCH), alacloro, heptacloro, metolacloro, aldrin, endrin, dieldrin, a e ß endosulfan, DDT e seus isômeros em solos de fragmentos da Mata Atlântica (Parque Nacional da Serra dos Órgãos - PARNASO) e em uma Micro-Bacia da região Serrana do Rio de Janeiro (Micro-Bacia do Córrego Sujo contribuinte do Rio Preto), comparando-se métodos de extração distintos. Foi realizada a extração dos POPs do solo por Soxhlet, ultrasom e microondas, seguida de etapa de clarificação (C18 e/ou Florisil) dos extratos das amostras para eliminação de interferentes da matriz, para posterior análise por cromatografia a gás acoplada com detector de captura de elétrons (ECD) para a identificação e quantificação dos POPs. A metodologia desenvolvida para a determinação de poluentes organoclorados persistentes em solos foi baseada nos procedimentos da US-EPA e validada de acordo com orientações sobre validação de métodos de ensaio químico do INMETRO. Foram obtidos os limites de detecção e quantificação tanto para o instrumento quanto para o método, para as diferentes matrizes sólidas e métodos de extração. A recuperação dos organoclorados em matrizes fortificadas utilizando os métodos de extração por Soxhlet, ultrasom e microondas apresentaram valores compreendidos entre 70 e 130 %, considerados aceitáveis para a análise de resíduos orgânicos em amostras ambientais. Observou-se para alguns analitos recuperações acima de 130 %, o que pode ser atribuído à contribuição da matriz, que apresenta elevados teores de matéria orgânica (8- 17 %). Foi realizado o estudo de recuperação dos analitos em solo de referência certificado (ERM®- CC007), mostrando resultados satisfatórios. Verificou-se que a extração assistida por radiação microondas, por ser a técnica mais energética, apresentou maiores valores de recuperação. A confirmação do indicativo de presença dos analitos de interesse nas amostras foi obtida pela troca da fase estacionária. Os resultados obtidos mostraram que os solos, coletados nas diversas áreas de estudo, apresentaram baixas concentrações de agrotóxicos organoclorados, e por isso estas áreas não foram consideradas como impactadas

Exploring chemical space in non-targeted analysis: a proposed ChemSpace tool

Non-targeted analysis (NTA) using high-resolution mass spectrometry allows scientists to detect and identify a broad range of compounds in diverse matrices for monitoring exposure and toxicological evaluation without a priori chemical knowledge. NTA methods present an opportunity to describe the constituents of a sample across a multidimensional swath of chemical properties, referred to as "chemical space." Understanding and communicating which region of chemical space is extractable and detectable by an NTA workflow, however, remains challenging and non-standardized. For example, many sample processing and data analysis steps influence the types of chemicals that can be detected and identified. Accordingly, it is challenging to assess whether analyte non-detection in an NTA study indicates true absence in a sample (above a detection limit) or is a false negative driven by workflow limitations. Here, we describe the need for accessible approaches that enable chemical space mapping in NTA studies, propose a tool to address this need, and highlight the different ways in which it could be implemented in NTA workflows. We identify a suite of existing predictive and analytical tools that can be used in combination to generate scores that describe the likelihood a compound will be detected and identified by a given NTA workflow based on the predicted chemical space of that workflow. Higher scores correspond to a higher likelihood of compound detection and identification in a given workflow (based on sample extraction, data acquisition, and data analysis parameters). Lower scores indicate a lower probability of detection, even if the compound is truly present in the samples of interest. Understanding the constraints of NTA workflows can be useful for stakeholders when results from NTA studies are used in real-world applications and for NTA researchers working to improve their workflow performance. The hypothetical ChemSpaceTool suggested herein could be used in both a prospective and retrospective sense. Prospectively, the tool can be used to further curate screening libraries and set identification thresholds. Retrospectively, false detections can be filtered by the plausibility of the compound identification by the selected NTA method, increasing the confidence of unknown identifications. Lastly, this work highlights the chemometric needs to make such a tool robust and usable across a wide range of NTA disciplines and invites others who are working on various models to participate in the development of the ChemSpaceTool. Ultimately, the development of a chemical space mapping tool strives to enable further standardization of NTA by improving method transparency and communication around false detection rates, thus allowing for more direct method comparisons between studies and improved reproducibility. This, in turn, is expected to promote further widespread applications of NTA beyond research-oriented settings