Headspace versus Direct Immersion Solid Phase Microextraction in Complex Matrixes: Investigation of Analyte Behavior in Multicomponent Mixtures

This document is the Accepted Manuscript version of a Published Work that appeared in final form in Analytical Chemistry, copyright © American Chemical Society after peer review and technical editing by the publisher. To access the final edited and published work see http://pubs.acs.org/doi/abs/10.1021/acs.analchem.5b01850This work aims to investigate the behavior of analytes in complex mixtures and matrixes with the use of solid-phase microextraction (SPME). Various factors that influence analyte uptake such as coating chemistry, extraction mode, the physicochemical properties of analytes, and matrix complexity were considered. At first, an aqueous system containing analytes bearing different hydrophobicities, molecular weights, and chemical functionalities was investigated by using commercially available liquid and solid porous coatings. The differences in the mass transfer mechanisms resulted in a more pronounced occurrence of coating saturation in headspace mode. Contrariwise, direct immersion extraction minimizes the occurrence of artifacts related to coating saturation and provides enhanced extraction of polar compounds. In addition, matrix-compatible PDMS-modified solid coatings, characterized by a new morphology that avoids coating fouling, were compared to their nonmodified analogues. The obtained results indicate that PDMS-modified coatings reduce artifacts associated with coating saturation, even in headspace mode. This factor, coupled to their matrix compatibility, make the use of direct SPME very practical as a quantification approach and the best choice for metabolomics studies where wide coverage is intended. To further understand the influence on analyte uptake on a system where additional interactions occur due to matrix components, ex vivo and in vivo sampling conditions were simulated using a starch matrix model, with the aim of mimicking plant-derived materials. Our results corroborate the fact that matrix handling can affect analyte/matrix equilibria, with consequent release of high concentrations of previously bound hydrophobic compounds, potentially leading to coating saturation. Direct immersion SPME limited the occurrence of the artifacts, which confirms the suitability of SPME for in vivo applications. These findings shed light into the implementation of in vivo SPME strategies in quantitative metabolomics studies of complex plant-based systems.The Natural Sciences and Engineering Research Council of Canada (NSERC) Sigma-Aldrich Corporatio

Advances in solid-phase microextraction as sample preparation method for food analysis.

Within all steps involved in the analytical process, sample preparation is considered the most time-consuming step. Therefore, substantial efforts have focused on the search for automated sample preparation strategies that minimize sample handling and errors associated with human interference. Solid phase microextraction (SPME) addresses well the necessity for simple and automated sample preparation, with the integration of sampling, extraction, clean up and instrumental introduction into a single step. In SPME, selective extraction of compounds takes place based on the degree of distribution of the analyte between the SPME coating and the sample matrix. For this reason, the correct choice of SPME coating for a given application has great influence on the acquisition of reliable analytical data. In spite of its great potential, the implementation of SPME in the analysis of complex matrices, such as food, has been hindered by the lack of suitable SPME coatings that possess compatibility with complex matrices while maintaining sufficient sensitivity for trace applications. The main problem resides in the fact that the most matrix compatible coating, PDMS, has limited extraction efficiency towards less hydrophobic analytes, whereas the coating that exhibits best extraction efficiency towards pesticides, in general, is PDMS/DVB. PDMS/DVB as a solid coating suffers from the attachment of matrix components onto the coating surface, known as fouling. Fouling does not only considerably shorten coating reusability, but it also causes significant changes in extraction efficiency, skewing the reliability of the data obtained. Therefore, in this thesis, a new approach to fabricate a matrix-compatible SPME coating for GC-based analysis of food matrices is presented. The developed matrix-compatible coating was evaluated for its reusability in complex matrices, namely grape pulp and Concord grape juice, as well as for its extraction capabilities towards various analytes bearing different physicochemical properties. First, a method to impart matrix-compatibility to commercially available solid SPME coatings was developed. The method consists of applying a thin layer of PDMS onto the solid coating, in this case PDMS/DVB. The main premise behind this approach was to create a coating that presents the matrix compatibility of PDMS, while maintaining the sensitivity obtained with PDMS/DVB. The reusability of the obtained PDMS-modified coating was evaluated in grape pulp, and rewarding results were obtained since the coating could be reused for over 100 extractions. Moreover, the PDMS-modified coating presented a similar extraction efficacy to that presented by the original PDMS/DVB coating towards the triazole pesticides, used as model analytes. The developed PDMS-modified coating was then employed to develop a simple and fast DI-SPME-GC-ToFMS method for determination of ten triazole fungicides in grapes and strawberries. The method was successfully validated, and the figures of merit obtained with the SPME method were compared to those obtained with the QuEChERS method. The limits of quantitation reached by SPME were at least one order of magnitude lower than those achieved by the QuEChERS method, whereas precision and accuracy were comparable for both methods. Subsequently, given the vast option of commercial PDMS blends available, different types of PDMS were compared for their reusability in complex matrices, and parameters associated with the PDMS-overcoated fiber fabrication were investigated in regards to their effect on fiber longevity. Results showed that the long-term reusability of such coatings is a function of the coating’s fabrication process, such as achievement of smooth and uniform PDMS surface, and sealing of both fiber ends by PDMS layer. Regarding PDMS type, best results were obtained with Sylgard ® 184. Since one of the most important branches of food analysis involves the simultaneous analysis of pesticides with a wide range of polarities and from different classes, the PDMS-modified coating was evaluated for the extraction of analytes of different polarities (log P = 1.43 to 6) from water samples in order to understand the mass transfer of analytes within the PDMS outer layer during the mass uptake process. Results showed that for hydrophobic analytes, the kinetics of extraction of the PDMS-modified coating are quite similar to that of the original PDMS/DVB. However, for more polar analytes, the rate-limiting step is the diffusion through the coating; therefore, the PDMS layer affects the kinetic uptake. The main implication of these results is quite evident if a method aiming at simultaneous determinations of both polar and non-polar analytes is to be developed, such as is the case in multiclass pesticide analysis, since the sensitivity of the method at too short extraction times might not be enough for polar analytes. Finally, once the PDMS-overcoated fibers were proven to be robust and compatible for use in fruit pulp, the DI-SPME-ToFMS method for multiresidue pesticide determination in grapes was developed and SPME parameters that can affect extraction efficiency were optimized via multivariate methods. Despite a thorough investigation during optimization, the most polar pesticides, acephate and omethoate, could not be detected. Next, a careful evaluation of internal standards was presented and attentively discussed. The results showed that two pairs of internal standards, interchangeable amongst them (i.e. only two internal standards were needed) were sufficient to ensure reliable, precise and accurate analytical data. Interestingly, only two internal standards at the time were needed, and among the choices presented, the use of non-deuterated compounds presents an affordable, cost-effective solution for the method. Next, the method was fully validated for 40 pesticides in compliance to EU/SANCO requirements (R2 > 0.995, RSD < 20%, and 80% < accuracy < 120%). The validated method exhibited excellent performance for pesticides such as chlorothalonil, dicofol, and folpet, which are considered the weak link in QuEChERS-based multiresidue methods. Pyrethroid pesticides were not validated due to their non-specific adsorption onto the vial walls. For pyrethroids, a solvent pre-extraction step should be incorporated in order to avoid losses due to the interaction of these compounds with glassware. Overall, despite the challenges and limitations encountered, it is evident that the practical aspects of the PDMS-modified coating demonstrated in this thesis create new opportunities for SPME applied in food analysis.1 yea

Capturing Plant Metabolome with Direct-Immersion in Vivo Solid Phase Microextraction of Plant Tissues

This document is the Accepted Manuscript version of a Published Work that appeared in final form in Analytical Chemistry, copyright © American Chemical Society after peer review and technical editing by the publisher. To access the final edited and published work see http://pubs.acs.org/doi/abs/10.1021/acs.analchem.5b03684 .For the first time, an in vivo sampling mode of direct immersion–solid phase microextraction (DI-SPME) was employed to capture the metabolome of living plant specimens, using apple (Malus × domestica Borkh.) as a model system. Metabolites were extracted from apple tissues and introduced by thermal desorption into a comprehensive two-dimensional gas chromatography–time-of-flight mass spectrometry instrument. The feasibility of this sampling approach, based on exploitation of microextraction principles, including negligible depletion of free analyte concentrations, solventless sampling and sample preparation, and on-site compatibility, was determined in global metabolite analysis. Rather than adopting an approach of traditional sample preparation, requiring metabolism quenching and laborious sample preparation, the objective of the study was to capture the metabolome in vivo, evaluate the feasibility of the approach to provide unbiased extraction coverage, and compare analytical precision when different SPME sampling modes are employed. The potential of in vivo DI-SPME in quantitative plant metabolomics was assessed by evaluating changes in metabolic fingerprints in response to fruit maturation. The in vivo SPME sampling approach has been demonstrated as capable of sampling living systems with high reproducibility, considering that nearly 50% of hundreds of evaluated compounds included in the determination of analytical performance met the 15% RSD FDA criterion. Esters were extracted with high repeatability (% RSD for hexyl butanoate and butyl butanoate of 16.5 and 5.9, respectively, from 9 determinations in 3 apples) and found to be upregulated in response to apple fruit maturation.Natural Sciences and Engineering Research Council of Canada (NSERC

English

&nbsp; Introduction: The early years of a child’s life are marked by a significant development, as well as high sensitivity to environmental influences such as poverty, housing, quality and family structure. Thus, the identification of environmental risk factors and delayed neurodevelopment, coupled with early intervention, are essential for an healthy development. Objective: To analyze the effect of environmental factors on the neuropsychomotor development of children in the Amazon community. Methods: This is a quantitative and qualitative study of analytical and cross-sectional approach with 50 children between 24 and 36 months of age, of both sexes, living in an Amazonian community. Two types of the socio-economic-environmental questionnaire were used; a) Infant/Toddler (IT) HOME Inventory to analyze the quality of the family environment; b) the Denver Screening Test II for screening neurodevelopment. Also, a descriptive analysis was performed using a calculation of means and standard deviations. Results: The study found that a significant majority of the children had normal neuropsychomotor development; however, children classified as delayed, the more significant impact variable in the development was the quality of the family environment, which in turn was influenced by the lower economic class, lack of water treatment, lack of electricity and external toilet. Conclusion: Environmental factors were not significant on the neuropsychomotor development of the local children of the Amazon community. &nbsp;&nbsp;Introdução: É Os primeiros anos da vida de uma criança são marcados por um importante desenvolvimento, além da alta sensibilidade às influências ambientais, como condições de pobreza e moradia e qualidade e estrutura familiar. Desta forma, a identificação de fatores de riscos ambientais e atrasos do desenvolvimento neuropsicomotor, somada a intervenção precoce, são essenciais para um desenvolvimento saudável. Objetivo: Analisar o efeito dos fatores ambientais no desenvolvimento neuropsicomotor de crianças em comunidade Amazônica. Método: Estudo quali-quantitativo do tipo transversal e analítico, realizado com 50 crianças entre 24 e 36 meses de idade, de ambos os sexos, residindo em uma comunidade Amazônica. Foram utilizados um questionário socioeconômico-ambiental, o Infant/Toddler (IT) HOME Inventory, para analisar a qualidade do ambiente familiar e o Teste de Triagem de Denver II, para triagem do desenvolvimento neuropsicomotor, e a análise descritiva dos dados foi feita utilizando o cálculo das médias e desvios padrão. Resultados: O estudo constatou que a maioria significativa das crianças apresentou o desenvolvimento neuropsicomotor normal, no entanto, das crianças classificadas com atraso, a variável de maior impacto no desenvolvimento foi a qualidade do ambiente familiar, que por sua vez sofreu influência da classe econômica inferior, falta de tratamento da água, ausência de energia elétrica e banheiro tipo externo. Conclusão: Os fatores ambientais não foram significativos perante o esenvolvimento&nbsp;neuropsicomotor&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; das crianças ribeirinhas da comunidade amazônica.&nbsp

DESENVOLVIMENTO DE EMPREENDIMENTOS COLETIVOS COM ÊNFASE NOS VALORES DA ECONOMIA SOLIDÁRIA: UM ESTUDO SOBRE A AMABELA

Este trabalho colabora com o estudo sobre a Economia Solidária (ES) e a organização AMABELA (Associação de Mulheres Trabalhadoras Rurais do Município de Belterra) realizado em Belterra-Pa com assessoria do projeto de Extensão Incubadora de Empreendimentos Solidários (IES) vinculado à Universidade Federal do Oeste do Pará (UFOPA). O papel do projeto IES é de intermediar a construção da autogestão dos empreendimentos econômicos solidários sobre bases não capitalistas. O objetivo da pesquisa foi apresentar como os princípios da Economia Solidária, compartilhados por meio da metodologia de incubação, contribuíram para que a AMABELA se identificasse como um empreendimento solidário para poder avançar no processo de autogestão. Os métodos utilizados foram pesquisa bibliográfica e pesquisa-ação com base nos relatórios da IES. A pesquisa é relevante, pois permite perceber a importância da autogestão para a AMABELA, uma vez que as associadas participam das atividades da associação, cooperando e se empenhando para o desenvolvimento desse empreendimento. Palavras-chave: autogestão; economia solidária; incubadora de empreendimentos solidários

Exposure To High Endotoxin Concentration Increases Wheezing Prevalence Among Laboratory Animal Workers: A Cross-sectional Study

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Endotoxin from Gram-negative bacteria are found in different concentrations in dust and on the ground of laboratories dealing with small animals and animal houses. Methods: Cross-sectional study performed in workplaces of two universities. Dust samples were collected from laboratories and animal facilities housing rats, mice, guinea pigs, rabbits or hamsters and analyzed by the "Limulus amebocyte lysate" (LAL) method. We also sampled workplaces without animals. The concentrations of endotoxin detected in the workplaces were tested for association with wheezing in the last 12 months, asthma defined by self-reported diagnosis and asthma confirmed by bronchial hyperresponsiveness (BHR) to mannitol. Results: Dust samples were obtained at 145 workplaces, 92 with exposure to animals and 53 with no exposure. Exposed group comprised 412 subjects and non-exposed group comprised 339 subjects. Animal-exposed workplaces had higher concentrations of endotoxin, median of 34.2 endotoxin units (EU) per mg of dust (interquartile range, 12.6-65.4), as compared to the non-exposed group, median of 10.2 EU/mg of dust (interquartile range, 2.6-22.2) (p < 0.001). The high concentration of endotoxin (above whole sample median, 20.4 EU/mg) was associated with increased wheezing prevalence (p < 0.001), i.e., 61 % of workers exposed to high endotoxin concentration reported wheezing in the last 12 months compared to 29 % of workers exposed to low endotoxin concentration. The concentration of endotoxin was not associated with asthma report or with BHR confirmed asthma. Conclusion: Exposure to endotoxin is associated with a higher prevalence of wheezing, but not with asthma as defined by the mannitol bronchial challenge test or by self- reported asthma. Preventive measures are necessary for these workers.1669Sao Paulo Research Foundation (FAPESP)National Council of Technological and Scientific Development (CNPq), BrazilFundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq

RECURSOS DIDÁTICOS PARA O ENSINO DE SURDOS EM CLASSES INCLUSIVAS

O artigo em tela objetiva apresentar recursos didáticos que podem ser utilizados em classes inclusivas com surdos. Para tanto, realizamos uma Revisão Sistemática da Literatura, tendo como base de dados os anais das quatro primeiras edições do Congresso Internacional de Educação Inclusiva (2014, 2016, 2018 e 2020) e, após a análise de 214 textos, selecionamos 11 para discorrer nesse escrito por se enquadrarem no escopo da pesquisa. Trata-se de uma pesquisa exploratória, com dados analisados a partir de uma abordagem qualitativa que nos permitiram observar a predominância de textos oriundos de pesquisadores vinculados a instituições do Nordeste do Brasil, bem como de pesquisas voltadas para ensino de Química e Física. Os recursos didáticos apresentados são de fácil produção e pautam-se na visualidade para a construção do conhecimento, desse modo, contribuem para o ensino de surdos e ouvintes

RECURSOS DIDÁTICOS PARA O ENSINO DE SURDOS EM CLASSES INCLUSIVAS

O artigo em tela objetiva apresentar recursos didáticos que podem ser utilizados em classes inclusivas com surdos. Para tanto, realizamos uma Revisão Sistemática da Literatura, tendo como base de dados os anais das quatro primeiras edições do Congresso Internacional de Educação Inclusiva (2014, 2016, 2018 e 2020) e, após a análise de 214 textos, selecionamos 11 para discorrer nesse escrito por se enquadrarem no escopo da pesquisa. Trata-se de uma pesquisa exploratória, com dados analisados a partir de uma abordagem qualitativa que nos permitiram observar a predominância de textos oriundos de pesquisadores vinculados a instituições do Nordeste do Brasil, bem como de pesquisas voltadas para ensino de Química e Física. Os recursos didáticos apresentados são de fácil produção e pautam-se na visualidade para a construção do conhecimento, desse modo, contribuem para o ensino de surdos e ouvintes