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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
21

Degradação de 2-clorofenol, 3-clorofenol, 2,4-cliclorofenol e acido 2,4-cliclorofenociacetato por Alcaligenes faecalis

Koehntopp, Paulo Ivo January 1998 (has links)
Dissertação (mestrado) - Universidade Federal de Santa Catarina, Centro de Ciencias Biologicas / Made available in DSpace on 2012-10-17T09:39:37Z (GMT). No. of bitstreams: 0Bitstream added on 2016-01-08T22:46:18Z : No. of bitstreams: 1 149226.pdf: 2176855 bytes, checksum: d0465e1062f8ee586bbd88dab3b9de9e (MD5) / Estudo da degradação de 2-clorofenol (2-CP), 3-clorofenol (3-CP), 2,4-diclorofenol (2,4DCP) e ácido 2,4-diclorofenoxiacetato (2,4-D) pela cepa Alcaligenes faecalís, degradadora de fenol e indução da capacidade de degradação na presença de fenol (co-metabolismo). Adaptações sucessivas de A. faecalis a 2-CP e 3-CP (16 mg/L) permitiram que estes compostos fossem totalmente consumidos, como única fonte de carbono, em 24 horas. No entanto, ensaios de adaptação apenas permitiram a degradação parcial de 4 mg/L de 2,4DCP e 2,4-D, em 48 horas. A suplementação do meio com extrato de levedura e glicose apenas reduziu o tempo de degradação dos diclorofenóis. Diferentes concentrações de fenol adicionados ao meio (co-metabolismo) reduziram o tempo de degradação total de todos os clorofenóis testados. Fenol (50 mg/L) demonstrou o melhor efeito na indução da capacidade de degradação dos clorofenóis. A cepa mostrou maior capacidade de consumir monoclorofenóis do que diclorofenóis, como única fonte de carbono.
22

Atividade antioxidante in vitro e perfil fenólico de cultivares de Mirtilo (Vaccinium sp.) produzidas no Brasil

Rodrigues, Eliseu January 2009 (has links)
Dissertação (mestrado) - Universidade Federal de Santa Catarina, Centro de Ciências Agrárias. Programa de Pós-Graduação em Ciência dos Alimentos. / Made available in DSpace on 2012-10-24T20:06:43Z (GMT). No. of bitstreams: 1 264168.pdf: 526639 bytes, checksum: 8aeeb5b18aaa827cecc51f7d9868c930 (MD5)
23

Atividade antioxidante in vitro e compostos fenólicos em morangos (Fragaria x ananassa Duch)

Copetti, Cristiane 25 October 2012 (has links)
Dissertação (mestrado) - Universidade Federal de Santa Catarina, Centro de Ciências Agrárias, Programa de Pós-Graduação em Ciência dos Alimentos, Florianópolis, 2010 / Made available in DSpace on 2012-10-25T02:41:47Z (GMT). No. of bitstreams: 1 281151.pdf: 506343 bytes, checksum: cc1cdd8ef98e72afb9a4ef68bd5e6638 (MD5) / Neste trabalho foram avaliados a atividade antioxidante, os compostos fenólicos e o conteúdo de minerais de cultivares de morango produzido nos sistemas de cultivo convencional e orgânico, provenientes do município de Rancho Queimado - SC, bem como pelo sistema hidropônico proveniente do Laboratório de Hidroponia, localizado no município de Florianópolis/SC. Foram coletadas amostras de morangos das cultivares Albion e Aromas durante a safra de 2008/2009 totalizando cinco meses de colheitas. No sistema hidropônico houve apenas uma colheita da cultivar Albion. A fim de avaliar a atividade antioxidante total foram utilizados os métodos ABTS (2,2´-azinobis(3-etilbenzotiazolina)-6-ácido sulfônico), DPPH (2,2-difenil-1 picrilhidrazila) e FRAP (poder de redução do ferro). O método Folin-Ciocalteau foi aplicado para quantificar os teores de fenólicos totais, o método DMACA (p-dimetilaminocinamaldeído) para os teores de flavanóis totais e para antocianinas monoméricas totais foi aplicado o método por diferença de pH. Os dados foram submetidos à análise de variância (ANOVA) e foi aplicado Tukey para determina avaliada para definir os agrupamentos das amostras de acordo com as variáveis estudadas. Os resultados mostraram que existe diferença significativa entre os sistemas de cultivo convencional, orgânico e hidropônico quanto ao conteúdo de compostos fenólicos, atividade antioxidante total (ABTS e FRAP) e conteúdo de alguns minerais. Entre as cultivares 'Albion' e Aromas houve diferença significativa apenas para a atividade antioxidante total medida pelo método DPPH, entretanto para os sistemas de cultivo convencional e orgânico, verificou-se diferença significativa para todos os parâmetros analisados. E quando comparados os diferentes períodos de colheita verificou-se influência destes nas variáveis estudadas. Os dados encontrados neste estudo sugerem que para um melhor aproveitamento nutricional dos fitoquímicos em morangos é preciso considerar não só os métodos de cultivo como também o período em que esse fruto é colhido. / In this paper the antioxidant activity, phenolic compounds and mineral contends of different cultivar of strawberry cultivated under conventional and organic agricultural systems obtained from Rancho Queimado # SC, as well as strawberry cultivated under hydroponic agricultural system obtained from Laboratory of Hydroponics, located at Florianópolis # SC were analyzed. Strawberries samples of cultivar #Albion# and #Aromas# during 2008/2009 harvest, totalizing five months, were collected. For the hydroponic system there was just one sample collect of cultivar #Albion#. In order to evaluate the total antioxidant activity, ABTS (2,2´-azinobis(3-etilbenzotiazolina)-6-sulfonic acid ), DPPH (2,2-difenil-1 picrilhidrazila) and FRAP (ferric reducing antioxidant p otential) methods were applied. Folin-Ciocalteau method was applied to quantify total phenolic compounds, DMACA (p-dimetilaminocinmaldeído) method was applied to quantify total flavanols and to quantify the total monomeric anthocyanins it was applied the pH difference method. The obtained data were submitted to the variance analysis (ANOVA) being applied the Tukey method to determine significance levels. Principal compounds analysis (PCA) was applied to define the sample groups according to the studied variables. Results showed a significant difference between conventional, organic and hydroponic agricultural system regarding phenolic compounds contends, total antioxidant activity (ABTS and FRAP) and contends of some minerals. Among cultivar #Albion# and #Aromas# there was significant difference only for total antioxidant activity measured by DPPH method, however for conventional and organic agricultural systems, it was verified a significant difference for all parameters analyzed. When the different harvest periods were compared, it was noticed the influence of them in the studied variables. Results found in this analysis, can suggest that for higher nutrition use of phytochemicals in strawberries it is necessary to consider not just the agricultural system but the harvest period as well.
24

Perfil metabólico primário (proteínas, amido e lipídeos) e secundário [carotenóides, antocianinas e ácidos (poli)fenólicos] de grãos de oito variedades crioulas de milho

Uarrota, Virgilio Gavicho 26 October 2012 (has links)
Dissertação (mestrado) - Universidade Federal de Santa Catarina. Programa de Pós-Graduação em Biotecnologia, Florianópolis, 2011 / Made available in DSpace on 2012-10-26T02:29:26Z (GMT). No. of bitstreams: 1 289413.pdf: 2202557 bytes, checksum: ffef042079a9d09712252f459fd872e4 (MD5) / O presente trabalho analisou o perfil metabólico primário (proteínas, amido e lipídeos ) e secundário (carotenóides, antocianinas e compostos fenólicos) de oito variedades crioulas de milho desenvolvidas por equenos agricultores do município de Anchieta (SC) e avaliou o efeito do ambiente sobre o teor daqueles metabólitos cultivando as mesmas variedades no campo experimental da UFSC (Florianópolis), assim como características fisico-químicas e funcionais das farinhas e amidos de variedades crioulas e hibridas de milho. Os resultados mostraram diferenças na composição química (proteínas e amido) detectadas por técnicas histoquimicas assim como pela quantificação do teor daqueles compostos nas amostras de variedades de milho (amido, proteínas e lipídeos). Maior ocorrência de polissacarídeos ácidos, amido, celulose e proteínas foi vista para as variedades desenvolvidas em Anchieta (Geração F0). A quantificação do teor de proteínas revelou F0 como sendo a geração de maior ocorrência daqueles compostos. As variedades crioulas MG-0, MPA1-1, LP-1, RXE-1 mostraram-se como fontes de apreciável teor de lipídeos. O tamanho dos grânulos dos amidos de variedades crioulas foi bastante heterogênea, na grande parte são circulares e apresentando fibras na matriz do amido. O poder de inchamento, índice de solubilidade, capacidade de retenção de água foram em geral baixos para as variedades crioulas de milho. Conteúdos superiores de amilose foram detectados para as variedades R8C-0, RJ-0 e Fortuna. A espectroscopia de infravermelho (FT-IR) aliada a quimiometria (PCAs) revelou a presença de proteínas, lipídeos, amido como sendo os compostos majoritários, no entanto, foi notório a presença de açúcares e compostos de metabolismo secundário (terpenóides). Baixas temperaturas de gelatinização foram observadas para as variedades MPA1 e RXE (F0) e valores elevados para LP e RJ (F0). Menores viscosidades das pastas de amidos form detectados para RJ, RXE, e PR (F0), no entanto, as variedades RJ e R8C apresentaram maior tendência a retrogradação. Em geral amidos de variedades da F1 apresentaram maior retrogradação. A análise do conteúdo de metabólitos secundários em sementes, folhas e flores femininas das variedades crioulas e hibridas revelou maiores teores de carotenóides para as variedades LP (folhas), RX (flores femininas) e RXE (sementes). A geração F1 apresentou maior teor médio de carotenóides comparativamente a F0 e variedades hibridas, revelando o efeito do ambiente na síntese daqueles compostos. O tratamento hidrotérmico aplicado na extração degradou os carotenóides. A CLAE, revelou serem as xantofilas (luteina e zeaxantina) os compostos majoritários em sementes de variedades crioulas, com destaque para as variedades RX, PR (F0), e PR, MG, RXE (F1). O teor de carotenóides foi superior na geração F1 assim como a sintese de a, e ß-carotenos, com destaque destes em PR, MG e RXE (F1). A variedade hibrida BR SC 154 revelou superioridade em carotenóides totais por CLAE comparativamente a todas outras estudadas. Teores elevados de antocianinas foram detectados em folhas, flores, e sementes das variedades PR, MG e LP-0 respectivamente, enquanto que, teores elevados de fenólicos totais foram observados em flores, folhas e grãos de RJ, RX e R8C-0 respectivamente. O estudo permitiu concluir que tanto amidos e farinhas das variedades F0, F1 e hibridas apresentaram algumas características desejáveis (alta viscosidade, baixa temperatura de empastamento, elevado teor de lipídios assim como teor médio de amilose) e podem ser usados para a obtenção de alguns produtos na indústria (Pães, pudins, sobremesas), fato que pode agregar mais valor, mais aplicabilidade e gerar novas perspectivas de uso destas variedades crioulas de milho e incentivo ao pequeno agricultor que vem desenvolvendo essas variedades ao longo de décadas. Variedades de milho crioulo exibiram quantidades apreciáveis de carotenóides, antocianinas e fenólicos existentes em diferentes partes da planta que vários outros relatos na literatura, e constituem ótimo material de exploração de compostos do metabolismo secundário para fins farmacêuticos, saúde e na indústria cosmética, fato que vai agregar mais valor e preservação deste germoplasma. / This study examined the primary metabolic profile (protein, starch and lipid) and secondary (carotenoids, anthocyanins and phenolics) of eight maize landraces developed by small farmers in the municipality of Anchieta (SC) and assessed the effect of environment on the metabolite content of those cultivating the same varieties in the experimental field of UFSC (Florianópolis). Physico-chemical and functional properties of flours and starches of maize landraces and hybrid varieties were also studied. The results showed differences in chemical composition (protein and starch) detected by histochemistry techniques as well as the quantification of the content of those compounds in the samples of maize varieties (starch, proteins and lipids). Increased occurrence of acidic polysaccharides, starch, cellulose and protein was seen for the maize landraces developed in Anchieta (F0 generation). The quantification of protein content revealed higher occurrence of those compounds for F0 generation. The landraces MG-0, MPA1-1, LP-1, RXE-1 appeared as sources of appreciable levels of lipids. The particle size of starches from landraces was very heterogeneous, in large part are circular and presenting fibers in the matrix of starch The swelling power, solubility index, and water holding capacity were generally low for maize landraces. Higher amylose content was detected for the varieties R8C-0, RJ-0 and Fortuna. Infrared spectroscopy (FTIR) coupled with chemometrics (PCA) revealed the presence of proteins, lipids, starch as the major components, however, was evident the presence of sugars and secondary metabolites compounds (terpenoids). Low gelatinization temperatures were observed for varieties MPA1 and RXE (F0) and high values for LP and RJ (F0). Lower viscosity of starch pastes were detected for RJ, RXE, and PR (F0), however, the varieties RJ, R8C showed higher retrogradation. In general the F1 varieties of starches showed higher retrogradation. The analysis of secondary metabolites in seeds, leaves and maize silks of landraces and hybrid showed higher levels of carotenoids for the varieties LP (leaves), RX (maize silks) and RXE (seeds). The F1 generation showed a higher average content of carotenoids compared to F0 and hybrid varieties, revealing the effect of environment on the synthesis of those compounds. The hydrothermal treatment degraded carotenoids extraction. HPLC revealed to be the xanthophylls (lutein and zeaxanthin) as the major components in seeds of local varieties, especially for RX, PR (F0), and PR, MG, RXE (F1). The carotene content was higher in the F1 generation as well as the synthesis of a, and ß-carotene, especially those in PR, MG and RXE (F1). The hybrid variety BR 154 SC showed superiority in carotenoids by HPLC compared to all other studied. High levels of anthocyanins were detected in leaves, maize silks, and seed varieties of PR, MG and LP-0, respectively, whereas high levels of phenolics were observed in maize silks, leaves and grains of RJ, R8C and RX-0 respectively. The study showed that both varieties of starches and flours of F0, F1 and hybrid had some desirable features (high viscosity, low temperature tightness, high fat content as well as medium amylose) and can be used to obtain certain products in industry (breads, puddings, desserts), which can add more value, more applicability and generate new prospects for using these varieties of maize and encouragement to the small farmer who has been developing along these varieties of maize landraces. Maize landraces presented appreciable amounts of carotenoids, anthocyanins and phenolic compounds detected in different plant parts than several other reports in the literature, and provide great raw materials of secondary metabolic compounds for pharmaceutical, health and cosmetics industry, a fact that will add more value and preservation this germplasm.This study examined the primary metabolic profile (protein, starch and lipid) and secondary (carotenoids, anthocyanins and phenolics) of eight maize landraces developed by small farmers in the municipality of Anchieta (SC) and assessed the effect of environment on the metabolite content of those cultivating the same varieties in the experimental field of UFSC (Florianópolis). Physico-chemical and functional properties of flours and starches of maize landraces and hybrid varieties were also studied. The results showed differences in chemical composition (protein and starch) detected by histochemistry techniques as well as the quantification of the content of those compounds in the samples of maize varieties (starch, proteins and lipids). Increased occurrence of acidic polysaccharides, starch, cellulose and protein was seen for the maize landraces developed in Anchieta (F0 generation). The quantification of protein content revealed higher occurrence of those compounds for F0 generation. The landraces MG-0, MPA1-1, LP-1, RXE-1 appeared as sources of appreciable levels of lipids. The particle size of starches from landraces was very heterogeneous, in large part are circular and presenting fibers in the matrix of starch The swelling power, solubility index, and water holding capacity were generally low for maize landraces. Higher amylose content was detected for the varieties R8C-0, RJ-0 and Fortuna. Infrared spectroscopy (FTIR) coupled with chemometrics (PCA) revealed the presence of proteins, lipids, starch as the major components, however, was evident the presence of sugars and secondary metabolites compounds (terpenoids). Low gelatinization temperatures were observed for varieties MPA1 and RXE (F0) and high values for LP and RJ (F0). Lower viscosity of starch pastes were detected for RJ, RXE, and PR (F0), however, the varieties RJ, R8C showed higher retrogradation. In general the F1 varieties of starches showed higher retrogradation. The analysis of secondary metabolites in seeds, leaves and maize silks of landraces and hybrid showed higher levels of carotenoids for the varieties LP (leaves), RX (maize silks) and RXE (seeds). The F1 generation showed a higher average content of carotenoids compared to F0 and hybrid varieties, revealing the effect of environment on the synthesis of those compounds. The hydrothermal treatment degraded carotenoids extraction. HPLC revealed to be the xanthophylls (lutein and zeaxanthin) as the major components in seeds of local varieties, especially for RX, PR (F0), and PR, MG, RXE (F1). The carotene content was higher in the F1 generation as well as the synthesis of a, and ß-carotene, especially those in PR, MG and RXE (F1). The hybrid variety BR 154 SC showed superiority in carotenoids by HPLC compared to all other studied. High levels of anthocyanins were detected in leaves, maize silks, and seed varieties of PR, MG and LP-0, respectively, whereas high levels of phenolics were observed in maize silks, leaves and grains of RJ, R8C and RX-0 respectively. The study showed that both varieties of starches and flours of F0, F1 and hybrid had some desirable features (high viscosity, low temperature tightness, high fat content as well as medium amylose) and can be used to obtain certain products in industry (breads, puddings, desserts), which can add more value, more applicability and generate new prospects for using these varieties of maize and encouragement to the small farmer who has been developing along these varieties of maize landraces. Maize landraces presented appreciable amounts of carotenoids, anthocyanins and phenolic compounds detected in different plant parts than several other reports in the literature, and provide great raw materials of secondary metabolic compounds for pharmaceutical, health and cosmetics industry, a fact that will add more value and preservation this germplasm.This study examined the primary metabolic profile (protein, starch and lipid) and secondary (carotenoids, anthocyanins and phenolics) of eight maize landraces developed by small farmers in the municipality of Anchieta (SC) and assessed the effect of environment on the metabolite content of those cultivating the same varieties in the experimental field of UFSC (Florianópolis). Physico-chemical and functional properties of flours and starches of maize landraces and hybrid varieties were also studied. The results showed differences in chemical composition (protein and starch) detected by histochemistry techniques as well as the quantification of the content of those compounds in the samples of maize varieties (starch, proteins and lipids). Increased occurrence of acidic polysaccharides, starch, cellulose and protein was seen for the maize landraces developed in Anchieta (F0 generation). The quantification of protein content revealed higher occurrence of those compounds for F0 generation. The landraces MG-0, MPA1-1, LP-1, RXE-1 appeared as sources of appreciable levels of lipids. The particle size of starches from landraces was very heterogeneous, in large part are circular and presenting fibers in the matrix of starch The swelling power, solubility index, and water holding capacity were generally low for maize landraces. Higher amylose content was detected for the varieties R8C-0, RJ-0 and Fortuna. Infrared spectroscopy (FTIR) coupled with chemometrics (PCA) revealed the presence of proteins, lipids, starch as the major components, however, was evident the presence of sugars and secondary metabolites compounds (terpenoids). Low gelatinization temperatures were observed for varieties MPA1 and RXE (F0) and high values for LP and RJ (F0). Lower viscosity of starch pastes were detected for RJ, RXE, and PR (F0), however, the varieties RJ, R8C showed higher retrogradation. In general the F1 varieties of starches showed higher retrogradation. The analysis of secondary metabolites in seeds, leaves and maize silks of landraces and hybrid showed higher levels of carotenoids for the varieties LP (leaves), RX (maize silks) and RXE (seeds). The F1 generation showed a higher average content of carotenoids compared to F0 and hybrid varieties, revealing the effect of environment on the synthesis of those compounds. The hydrothermal treatment degraded carotenoids extraction. HPLC revealed to be the xanthophylls (lutein and zeaxanthin) as the major components in seeds of local varieties, especially for RX, PR (F0), and PR, MG, RXE (F1). The carotene content was higher in the F1 generation as well as the synthesis of a, and ß-carotene, especially those in PR, MG and RXE (F1). The hybrid variety BR 154 SC showed superiority in carotenoids by HPLC compared to all other studied. High levels of anthocyanins were detected in leaves, maize silks, and seed varieties of PR, MG and LP-0, respectively, whereas high levels of phenolics were observed in maize silks, leaves and grains of RJ, R8C and RX-0 respectively. The study showed that both varieties of starches and flours of F0, F1 and hybrid had some desirable features (high viscosity, low temperature tightness, high fat content as well as medium amylose) and can be used to obtain certain products in industry (breads, puddings, desserts), which can add more value, more applicability and generate new prospects for using these varieties of maize and encouragement to the small farmer who has been developing along these varieties of maize landraces. Maize landraces presented appreciable amounts of carotenoids, anthocyanins and phenolic compounds detected in different plant parts than several other reports in the literature, and provide great raw materials of secondary metabolic compounds for pharmaceutical, health and cosmetics industry, a fact that will add more value and preservation this germplasm.This study examined the primary metabolic profile (protein, starch and lipid) and secondary (carotenoids, anthocyanins and phenolics) of eight maize landraces developed by small farmers in the municipality of Anchieta (SC) and assessed the effect of environment on the metabolite content of those cultivating the same varieties in the experimental field of UFSC (Florianópolis). Physico-chemical and functional properties of flours and starches of maize landraces and hybrid varieties were also studied. The results showed differences in chemical composition (protein and starch) detected by histochemistry techniques as well as the quantification of the content of those compounds in the samples of maize varieties (starch, proteins and lipids). Increased occurrence of acidic polysaccharides, starch, cellulose and protein was seen for the maize landraces developed in Anchieta (F0 generation). The quantification of protein content revealed higher occurrence of those compounds for F0 generation. The landraces MG-0, MPA1-1, LP-1, RXE-1 appeared as sources of appreciable levels of lipids. The particle size of starches from landraces was very heterogeneous, in large part are circular and presenting fibers in the matrix of starch The swelling power, solubility index, and water holding capacity were generally low for maize landraces. Higher amylose content was detected for the varieties R8C-0, RJ-0 and Fortuna. Infrared spectroscopy (FTIR) coupled with chemometrics (PCA) revealed the presence of proteins, lipids, starch as the major components, however, was evident the presence of sugars and secondary metabolites compounds (terpenoids). Low gelatinization temperatures were observed for varieties MPA1 and RXE (F0) and high values for LP and RJ (F0). Lower viscosity of starch pastes were detected for RJ, RXE, and PR (F0), however, the varieties RJ, R8C showed higher retrogradation. In general the F1 varieties of starches showed higher retrogradation. The analysis of secondary metabolites in seeds, leaves and maize silks of landraces and hybrid showed higher levels of carotenoids for the varieties LP (leaves), RX (maize silks) and RXE (seeds). The F1 generation showed a higher average content of carotenoids compared to F0 and hybrid varieties, revealing the effect of environment on the synthesis of those compounds. The hydrothermal treatment degraded carotenoids extraction. HPLC revealed to be the xanthophylls (lutein and zeaxanthin) as the major components in seeds of local varieties, especially for RX, PR (F0), and PR, MG, RXE (F1). The carotene content was higher in the F1 generation as well as the synthesis of a, and ß-carotene, especially those in PR, MG and RXE (F1). The hybrid variety BR 154 SC showed superiority in carotenoids by HPLC compared to all other studied. High levels of anthocyanins were detected in leaves, maize silks, and seed varieties of PR, MG and LP-0, respectively, whereas high levels of phenolics were observed in maize silks, leaves and grains of RJ, R8C and RX-0 respectively. The study showed that both varieties of starches and flours of F0, F1 and hybrid had some desirable features (high viscosity, low temperature tightness, high fat content as well as medium amylose) and can be used to obtain certain products in industry (breads, puddings, desserts), which can add more value, more applicability and generate new prospects for using these varieties of maize and encouragement to the small farmer who has been developing along these varieties of maize landraces. Maize landraces presented appreciable amounts of carotenoids, anthocyanins and phenolic compounds detected in different plant parts than several other reports in the literature, and provide great raw materials of secondary metabolic compounds for pharmaceutical, health and cosmetics industry, a fact that will add more value and preservation this germplasm.This study examined the primary metabolic profile (protein, starch and lipid) and secondary (carotenoids, anthocyanins and phenolics) of eight maize landraces developed by small farmers in the municipality of Anchieta (SC) and assessed the effect of environment on the metabolite content of those cultivating the same varieties in the experimental field of UFSC (Florianópolis). Physico-chemical and functional properties of flours and starches of maize landraces and hybrid varieties were also studied. The results showed differences in chemical composition (protein and starch) detected by histochemistry techniques as well as the quantification of the content of those compounds in the samples of maize varieties (starch, proteins and lipids). Increased occurrence of acidic polysaccharides, starch, cellulose and protein was seen for the maize landraces developed in Anchieta (F0 generation). The quantification of protein content revealed higher occurrence of those compounds for F0 generation. The landraces MG-0, MPA1-1, LP-1, RXE-1 appeared as sources of appreciable levels of lipids. The particle size of starches from landraces was very heterogeneous, in large part are circular and presenting fibers in the matrix of starch The swelling power, solubility index, and water holding capacity were generally low for maize landraces. Higher amylose content was detected for the varieties R8C-0, RJ-0 and Fortuna. Infrared spectroscopy (FTIR) coupled with chemometrics (PCA) revealed the presence of proteins, lipids, starch as the major components, however, was evident the presence of sugars and secondary metabolites compounds (terpenoids). Low gelatinization temperatures were observed for varieties MPA1 and RXE (F0) and high values for LP and RJ (F0). Lower viscosity of starch pastes were detected for RJ, RXE, and PR (F0), however, the varieties RJ, R8C showed higher retrogradation. In general the F1 varieties of starches showed higher retrogradation. The analysis of secondary metabolites in seeds, leaves and maize silks of landraces and hybrid showed higher levels of carotenoids for the varieties LP (leaves), RX (maize silks) and RXE (seeds). The F1 generation showed a higher average content of carotenoids compared to F0 and hybrid varieties, revealing the effect of environment on the synthesis of those compounds. The hydrothermal treatment degraded carotenoids extraction. HPLC revealed to be the xanthophylls (lutein and zeaxanthin) as the major components in seeds of local varieties, especially for RX, PR (F0), and PR, MG, RXE (F1). The carotene content was higher in the F1 generation as well as the synthesis of a, and ß-carotene, especially those in PR, MG and RXE (F1). The hybrid variety BR 154 SC showed superiority in carotenoids by HPLC compared to all other studied. High levels of anthocyanins were detected in leaves, maize silks, and seed varieties of PR, MG and LP-0, respectively, whereas high levels of phenolics were observed in maize silks, leaves and grains of RJ, R8C and RX-0 respectively. The study showed that both varieties of starches and flours of F0, F1 and hybrid had some desirable features (high viscosity, low temperature tightness, high fat content as well as medium amylose) and can be used to obtain certain products in industry (breads, puddings, desserts), which can add more value, more applicability and generate new prospects for using these varieties of maize and encouragement to the small farmer who has been developing along these varieties of maize landraces. Maize landraces presented appreciable amounts of carotenoids, anthocyanins and phenolic compounds detected in different plant parts than several other reports in the literature, and provide great raw materials of secondary metabolic compounds for pharmaceutical, health and cosmetics industry, a fact that will add more value and preservation this germplasm.
25

Estudo de Brettanomyces/Dekkera e etil-fenóis em vinhos tintos brasileiros / Study of brettanomyces/dekkera and ethylphenols in brazilian red wines

Ávila, Larissa Dias de January 2010 (has links)
A levedura Brettanomyces/Dekkera pode causar alterações importantes em vinhos tintos, com a formação de etil-fenóis, compostos de aromas desagradáveis. Este estudo teve como objetivo determinar a presença dessa levedura e de etil-fenóis em vinhos tintos comerciais e durante a vinificação em escala industrial, além de observar sua possível inibição pelo ácido sórbico. Brettanomyces/Dekkera foi quantificada em meio seletivo, e etil-fenóis, por cromatografia gasosa. SO2 livre e total, álcool, extrato seco total, açúcares residuais, acidez total e volátil e pH também foram determinados. O crescimento durante a vinificação foi acompanhado usando diferentes meios seletivos. Dekkera bruxellensis (NRRL Y – 12961) e leveduras isoladas de vinhos brasileiros foram cultivadas em meio sintético e vinho, contendo ácido sórbico entre 0 e 250 mg/L. Das 126 amostras de vinhos comerciais, 26,98% apresentaram Brettanomyces/Dekkera, e 46,03%, etil-fenóis acima do limiar de 426 μg/L, com SO2 e álcool mostrando-se como fatores limitantes. A passagem dos vinhos por barricas e as variedades de uva não influenciaram os níveis de contaminação e de etil-fenóis. Durante a vinificação, Brettanomyces/Dekkera foi detectada a partir do mosto. A baixa população não foi suficiente para formar etil-fenóis durante cinco meses após o esmagamento. Os meios não foram completamente seletivos, especialmente para uvas e mostos. O ácido sórbico inibiu a cepa de Dekkera bruxellensis (NRRL Y – 12961), especialmente para concentrações acima de 150 mg/L, sendo variável o grau de inibição para os isolados. / The yeast Brettanomyces/Dekkera can cause significant spoilage in red wines, with the production of ethylphenols, compounds of unpleasant odors. This study aimed at determining the presence of this yeast and ethylphenols in commercial red wines during vinification in industrial scale and to observe its possible inhibition by sorbic acid. Brettanomyces/Dekkera was quantified on selective medium, while ethyphenols were quantified by gas chromatography. Free and total SO2, alcohol, total dry extract, residual sugar, total and volatile acidity, and pH were also determined. The growth during winemaking was followed using different selective media. Dekkera bruxellensis (NRRL Y – 12961) and Brazilian wines yeasts were grown in synthetic medium and in wine, containing sorbic acid between 0 and 250 mg/L. Brettanomyces/Dekkera was present in 26.98% of the 126 samples of commercial wines. The ethylphenols were above of the 426 μg/L threshold in 46.03% of the samples. SO2 and alcohol were limiting factors. The stage in barrels and the varieties did not affect the levels of contamination and ethylphenols. During winemaking, Brettanomyces/Dekkera was detected from the must. The low population was not enough to produce ethylphenols in five months after crushing. The media were not completely selective, especially for grapes and musts. Sorbic acid inhibited the strains of Dekkera bruxellensis (NRRL Y – 12961), especially at concentrations above 150 mg/L, with variable degree of inhibition for the isolates.
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Avaliação da atividade anti-rábica in vitro de compostos fenólicos sintéticos

Chávez, Juliana Helena January 2005 (has links)
Dissertação (mestrado) - Universidade Federal de Santa Catarina. Programa de Pós-Graduação em Biotecnologia. / Made available in DSpace on 2013-07-16T02:00:32Z (GMT). No. of bitstreams: 1 223441.pdf: 2772291 bytes, checksum: ad47726fad89085141b9c3d6ce889814 (MD5) / A raiva humana é uma doença de etiologia viral com grande impacto na saúde pública, principalmente por seu curso fatal, na grande maioria dos casos. Apesar da difundida e estabelecida profilaxia através da vacinação, acredita-se que a raiva seja responsável por aproximadamente 40.000 a 70.000 mortes por ano, especialmente em áreas endêmicas. Atualmente, não há disponibilidade de qualquer fármaco antiviral com ação específica contra o vírus rábico. Em combinação com a profilaxia, um fármaco antiviral poderia ser usado para o tratamento da raiva humana e aumentar a proteção contra a encefalite causada pelo vírus. Os compostos fenólicos (CF) são derivados do metabolismo vegetal secundário, podendo ser obtidos através de síntese. Muitos estudos demonstraram que os CF possuem inúmeras atividades farmacológicas, incluindo ações vasodilatadora, antialérgica, antiinflamatória, antiviral, entre outras. Neste trabalho, a potencial atividade anti-rábica in vitro de 24 CF foi avaliada utilizando-se células McCoy e a cepa PV do vírus rábico. A citotoxicidade (CC50) foi determinada pelo ensaio colorimétrico do MTT e a atividade anti-rábica (CE50) foi estimada através da técnica de inibição do efeito citopático viral. Isoprinosina e quetamina foram utilizadas como controles positivos. A padronização do ensaio do MTT para avaliação da atividade anti-rábica também foi realizada, mas os resultados mostraram que este ensaio é inadequado para tal avaliação. Os compostos testados apresentaram índices de seletividade (IS= CC50/CE50) que variaram de 1,0 a 3,9. Seis CF não inibiram o efeito citopático viral em qualquer grau, em concentrações = a seus valores de CC50. Quatro CF apresentaram valores de IS > 3,0. Através dos resultados obtidos, foram sugeridas algumas possíves relações estrutura-atividade. Observou-se que a presença de hidroxilas livres e de grupamentos éteres influenciou a atividade anti-rábica. Contudo, estudos adicionais são necessários para o estabelecimento dessa relação.
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Atividade antioxidante e identificação dos ácidos fenólicos do gengibre (Zingiber officinale ROSCOE)

Beal, Bianca Helena January 2006 (has links)
Dissertação (mestrado) - Universidade Federal de Santa Catarina, Centro de Ciências Agrárias. Programa de Pós-Graduação em Ciência dos Alimentos. / Made available in DSpace on 2012-10-22T08:32:30Z (GMT). No. of bitstreams: 1 231714.pdf: 2439985 bytes, checksum: 7ba5bbe67c59e45c6ebdc5101e9f8e98 (MD5) / Os extratos etéreo, acetônico, alcoólico e aquoso de gengibre (Zingiber officinale Roscoe) foram avaliados quanto ao conteúdo de compostos fenólicos totais e atividade antioxidante, tendo como objetivo observar a influência de cada solvente extrator e da época de colheita sobre esses parâmetros. Para isto, as amostras de gengibre coletadas em dois períodos de colheita diferentes foram submetidas a análises com o método de Folin - Ciocalteau, o qual quantifica os fenólicos totais da amostra; ao método com o radical ABTS (2,2´-azinobis(3-etilbenzotiazolina-6-ácido sulfônico) e ao sistema de cooxidação ß-caroteno/ácido linoléico, os quais medem a atividade antioxidante de cada extrato, sendo que o último foi também utilizado para avaliar o efeito sinérgico entre as amostras e o antioxidante sintético BHT (butil hidroxitolueno). Os resultados indicaram uma boa capacidade antioxidante dos extratos etéreo e aquoso, principalmente nos extratos da amostras coletadas próximas ao fim do período de colheita. Pode ser observada uma correlação linear entre o conteúdo de compostos fenólicos e atividade antioxidante (r2=0,9590). Também foi demonstrado o sinergismo entre os extratos aquosos a 200 ppm e o BHT, apresentando aproximadamente 90% de inibição do processo oxidativo. As amostras de gengibre também foram fracionadas em: ácidos fenólicos livres, ésteres solúveis e insolúveis a fim de identificar os ácidos fenólicos presentes em cada fração. Essas frações foram submetidas à análise cromatográfica, além da avaliação quanto ao seu potencial antioxidante, através do método ABTS, e quanto ao conteúdo de fenólicos totais, de acordo com o método Folin-Ciocalteau. Observou-se uma boa quantidade de compostos fenólicos totais nas frações, variando de 846,37 a 1409,05 mg GAE (equivalentes em ácido gálico) por 100 g de amostra (peso seco). As frações foram submetidas à cromatografia gasosa e a quantificação foi baseada nos tempos de retenção dos padrões de ácidos fenólicos. Uma alta quantidade de ácido salicílico foi encontrada em todas as frações, com valores variando entre 75% e 98%. Outros ácidos, como o caféico, ferúlico, sináptico e gálico também foram encontrados nas frações, e sua presença pode ter influência sobre a atividade antioxidante total do gengibre, já que o ácido salicílico não possui atividade por si só. Os resultados indicam que o gengibre pode ser uma potencial fonte de antioxidantes naturais, possivelmente podendo ser utilizado como substituinte aos antioxidantes sintéticos amplamente utilizados pela indústria de alimentos, tendo em consideração a preocupação dos consumidores com a toxicidade desses aditivos. The etheric, acetonic, alcoholic and aqueous extracts of ginger (Zingiber officinale Roscoe) had their total phenolic content and antioxidant activity evaluated, aiming to observe the influence of the extraction solvent and the harvest time over these parameters. Thus, the ginger samples collected in two different harvest times were submitted to analysis with the Folin - Ciocalteau method, which quantifies the total phenolic contento f the samples; to the ABTS (2,2´-azinobis(3-ethylbenzothyazoline-6-sulphonic acid) method and to the cooxidation system ß-carotene/linoleic acid, which measures the antioxidant activity of each extract, considering that the last was also used to evaluate the synergism within the samples and the synthetic antioxidant BHT (butyl hydroxytoluene). The results indicated a high antioxidant capacity of the etheric and aqueous extracts, mainly in the extracts of the samples collected close to the end of the harvest time. A linear correlation could be observed within the total phenolic content and the antioxidant activity (r2=0,9590). The synergism among the aqueous extracts and BHT could also be observed, showing approximately 90% of oxidation inhibition. The ginger samples were also fractionated to: free phenolic acids, esterified soluble bound and insoluble bound phenolic acids in order to identify the phenolic acids present in each fraction. These samples were submitted to chromatographic analysis, and also for the evaluation of their antioxidant potential, through ABTS method, and total phenolic content, according to Folin-Ciocalteau´s method. A high quantity of total phenolics could be observed, varying from 846,37 to 1409,05 mg GAE (gallic acid equivalent) per 100 g of the sample (dry weight). The fractions were submitted to gas-chromatography and the quantification was based on the retention times of the phenolic acids standards. A high quantity of salicylic acid was found in all the fractions, which values varied from 75% to 98%. Some other acids, as caffeic, ferulic, synaptic and gallic were also found in the fractions, and their presence can influence the total antioxidant activity of ginger, considering that salicylic acid has no activity itself. The results indicate that ginger could be a potential source of natural antioxidants, possibly being utilized as a substitute for the synthetic antioxidants widely used by the food industry, considering the concerns on the toxicity of these additives.
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Potencial antioxidante e compostos fenólicos na cerveja, chopp, cevada (Hordeum vulgare L.) e no bagaço de brassagem

Freitas, Gisele Laisa January 2006 (has links)
Dissertação (mestrado) - Universidade Federal de Santa Catarina, Centro de Ciências Agrárias. Programa de Pós-Graduação em Ciência dos Alimentos. / Made available in DSpace on 2012-10-22T08:41:16Z (GMT). No. of bitstreams: 1 231715.pdf: 724421 bytes, checksum: 248b669693bd8a4c9c4a455395634c5e (MD5) / O consumo moderado e constante de alguns compostos naturalmente presentes nos alimentos pode ser responsável por diversos efeitos favoráveis a saúde. Importantes pesquisas são realizadas visando avaliar a possível contribuição que os antioxidantes presentes na dieta podem ter na prevenção de diversas doenças. A composição da cerveja, se destaca pela presença de vitaminas, proteínas e compostos fenólicos, provenientes geralmente da sua matéria-prima. Este estudo teve como objetivo investigar o potencial antioxidante e compostos fenólicos de cervejas distintas, bem como analisar sua principal matéria-prima, cevada, e o subproduto gerado, bagaço de brassagem na sua forma úmida e seca. Tanto para as cervejas como para a cevada e o bagaço foram realizadas as análises para determinação da atividade antioxidante, através dos métodos químicos: ABTS (ácido 2,2'-azino-bis (3-etilbenzotiazolin 6-sulfônico) e o DPPH (2,2- Difenil-1-picrilhidrazilo), e para os compostos fenólicos totais o método de Folin-Ciocalteu e para determinar os flavanóis o método DMACA. Com o intuito de determinar se o bagaço de brassagem, denominado também como resíduo do processamento, pode ser reaproveitado realizou-se o estudo da sua composição centesimal. A cevada e o bagaço de brassagem foram analisados após obtenção de extratos com três diferentes solventes (acetona, água e etanol), pelo método de extração seqüencial e também por extração direta com acetona, em diferentes concentrações. O solvente extrator de maior desempenho foi a acetona 70%, medida através do método ABTS. Na cerveja, os compostos fenólicos podem variar de 249,73 a 808,58 mg GAE/L, em ordem crescente a cerveja escura de trigo, apresenta os maiores valores de polifenóis totais, seguida das cervejas escura de cevada, das cervejas clara de trigo e das cervejas clara de cevada. Apresentando valores de atividade antioxidante equivalente ao Trolox, TEAC (método ABTS), que variaram de 1048,62 a 3957,97µMol TEAC/L e pelo método DPPH, de 1051,98 a 3015,29 µMol TEAC/L. Enquanto que no chopp de cevada, o conteúdo de compostos fenólicos pode variar de 314,3-360,7 mg GAE/L, e atividade antioxidante (método ABTS) média de 2113,02 µMol TEAC/L (lote 3). Na cevada o conteúdo médio de polifenóis totais foi 292 mg (GAE)/100g, e de atividade antioxidante 1779,75 µMol TEAC/100g. Considerável conteúdo total de compostos fenólicos permanecem no bagaço, em média 114,81 mg GAE/100g de amostra no bagaço úmido e 180,58 mg GAE/100g de amostra no bagaço seco, ambos obtidos pela extração seqüencial, e a atividade antioxidante no bagaço úmido varia de 98,92 a 427,99 µMol TEAC/100g e de 167,26 a 680,81 µMol TEAC/100g de bagaço seco. Os resultados obtidos demonstraram que existe correlação entre a atividade antioxidante e os compostos fenólicos, na cerveja e no chopp, assim como na cevada e no bagaço de brassagem. As cervejas analisadas podem ser fonte de compostos fenólicos aos quais se atribui a atividade antioxidante. A moderate and constant consumption of some naturally present compounds in foods can be responsible for some favorable effects to the health. Nowadays, there are many researches aiming to evaluate the possible contributions that antioxidants originating from diet could have on the prevention of diverse diseases. Compounds that are proeminent in beer composition are vitamins, proteins and phenolic compounds, usually procceding from its raw material. The objective of this study was to investigate the antioxidant potential and phenolic compounds from different types of beers, as well as analyse its principal raw material, barley, and the subproduct generated, brassage pomace in its humid and dried form. As much in the beers as in the barley, analyses for the determination of antioxidant activity were determined using both methods: ABTS (2,2'-azino-bis (3-ethylbenzothyazoline 6-sulphonic acid) and DPPH (2,2- diphenyl-1-picrylhydrazil); for the total phenolic content, the Folin-Ciocalteu´s method; for the determination of flavanols, the flavanols,the DMACA method. With the intention of determining if the brassage pomace, also called processing residue, could be reused, the centesimal composition analysis was carried out. The barley and bagasse pomace were analysed after attainment of their extracts using three different solvents: acetone, water and ethanol, using the sequential extraction method and also through direct extraction with acetone in different concentrations. The extraction solvent with better performance, acetone 70%, was obtained with the ABTS method. In the beers, the phenolic compounds varied from 249,73 to 808,58 mg GAE/L, in crescent order the dark wheat beer presented the highest poliphenolic values, followed by dark barley beer, clear wheat beer and clear barley beer, presenting trolox equivalent antioxidant activities, TEAC (ABTS method), which varied from 1048,62 to 3957,97µMol TEAC/L and with the DPPH method, from 1051,98 to 3015,29 µMol TEAC/L. While in barley fresh beer, the total phenolic content varied from 314,3-360,7 mg GAE/L, and antioxidant activity (ABTS method) means varied from 2113,02 µMol TEAC/L (allotment 3). In the barley, the total phenolic content mean was 292 mg (GAE)/100g, and antioxidant activity was 1779,75 µMol TEAC/100g. A high total phenolic content could be observed in the pomace, which mean was 114,81 mg GAE/100g in the humid pomace and 180,58 mg GAE/100g in the dried pomace, both obtained by the sequential extraction, and the antioxidant activity of the humid pomace varied from 98,92 to 427,99 µMol TEAC/100g and from 167,26 to 680,81 µMol TEAC/100g in the dried pomace. The results obtained show that there is correlation between the antioxidant activity and phenolic compounds in beer and fresh beer, as well as in the barley and brassage pomace. The beers analysed could be a potential source of phenolic compounds to which the total antioxidant activity is attributed.
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Determinação eletroanalítica de compostos fenólicos utilizando um eletrodo de pasta de carbono modificado com poli(vinilpirrolidona)

Piovesan, Jamille Valéria January 2014 (has links)
Dissertação (mestrado) - Universidade Federal de Santa Catarina, Centro de Ciências Físicas e Matemáticas, Programa de Pós-Graduação em Química, Florianópolis, 2014. / Made available in DSpace on 2014-08-06T18:00:53Z (GMT). No. of bitstreams: 1 326893.pdf: 1676152 bytes, checksum: d926941fded46ee790891c6c2ec3b908 (MD5) Previous issue date: 2014 / Abstract : A carbon paste electrode modified with poly (vinylpyrrolidone) polymer was used to study the electrochemical quercetin and kaempferol and the electroanalytical determination of phenol compounds and in pharmaceutical vegetable matrices. About this electrode , cyclic voltammograms of quercetin presented three oxidation peaks located at +0.32 , +0.78 and +1.04 V. The electro-oxidation in the first peak leads to the formation of the corresponding ortho-quinone, which can be reduced in favorable experimental conditions. Under these favorable conditions, the reaction is quasi-reversible, and the process is controlled by diffusion. This behavior has been exploited for the electroanalytical determination of quercetin by square-wave voltammetry. The calibration curve obtained for quercetin was linear in the concentration range from 0.5 to 5.5 mmol L-1 (R2 = 0.998). The limits of detection and quantification were 0.17 ?mol L-1 and 0.52 ?mol L-1, respectively. The sensor was used for the determination of quercetin in pharmaceuticals. The accuracy of the results provided by the sensor was evaluated by comparison with the results obtained by UV-vis technique. The sensor was also applied to study the electrochemical behavior of kaempferol and quantification of phenolic compounds in plant samples. About this electrode, cyclic voltammograms for kaempferol showed only one oxidation peak at +0.58 V and a signal reduction in +0.46 V. Under favorable conditions, the reaction is quasi-reversible, and the process is controlled by diffusion. The calibration curve for the kaempferol showed two linear ranges in concentration ranges of 0.05 to 0.50 ?mol L-1 and 0.50 to 6.0 ?mol L-1 (R2 = 0.980). Using the most sensitive range, the limits of detection and quantification were 45.0 nmol L-1 and 138.0 nmol L-1, respectively. The sensor was applied to the electroanalytical determination of phenolics by square-wave voltammetry compounds in plant samples. The content of total phenolic compounds were expressed in terms of kaempferol (CE)/g of plant in nature mg. The plant that showed a higher content of phenolics was spinach (0.32 mg g-1), followed by the cauliflower (0.29 mg g-1), broccoli (0.21 mg g-1) and, finally, with lower concentrations, chicory (0.08 mg g-1). The accuracy of the results provided by the sensor was evaluated by comparison with the results obtained by Folin-Ciocalteau method.
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Desenvolvimento de eletrodos quimicamente modificados com silsesquioxano para detecção seletiva de isômeros de compostos fenólicos

Silva, Paulo Sérgio da January 2014 (has links)
Tese (doutorado) - Universidade Federal de Santa Catarina, Centro de Ciências Físicas e Matemáticas, Programa de Pós-graduação em Química, 2014 / Made available in DSpace on 2015-02-05T20:34:11Z (GMT). No. of bitstreams: 1 331653.pdf: 3938102 bytes, checksum: 906f8951a81a8c26b50a17f18b4506aa (MD5) Previous issue date: 2014 / Neste trabalho, dois diferentes eletrodos quimicamente modificados foram desenvolvidos utilizando o polímero cloreto de 3-n-propil-4-picolina silsesquioxano (Si4Pic+Cl-), os quais foram aplicados na detecção seletiva de isômeros de compostos fenólicos. No primeiro caso, um eletrodo de pasta de carbono (do inglês, carbon paste electro de - CPE) foi modificado com a forma insolúvel em água do Si4Pic+Cl-, o qual foi denominado CPE/Si4Pic+Cl-. Este eletrodo foi empregado como sensor eletroquímico na detecção de isômeros do dihidroxibenzeno utilizando voltametria de pulso diferencial (do inglês, differential pulse voltammetry - DPV). A separação entre os potenciais de pico de oxidação da hidroquinona (HQ) e do catecol (CC) foi suficiente (114 mV) para realizar uma detecção seletiva. As curvas de calibração obtidas foram lineares na faixa de concentração de 10,0 a 450,0 µmol L-¹ para a HQ (R = 0,9983) e de 10,0 a 300,0 µmol L-¹ para o CC (R = 0,9974). O limite de detecção foi de 10,0 µmol L-¹ para ambos os isômeros. Além disso, o CPE/Si4Pic+Cl- apresentou uma boa estabilidade e repetibilidade, mostrando-se um sensor eletroquímico promissor para detecção seletiva destes compostos. Já no segundo caso, a forma solúvel em água do Si4Pic+Cl- foi utilizada como estabilizante de nanopartículas de ouro (AuNPs). A solução coloidal obtida (AuNPs-Si4Pic+Cl-) contendo AuNPs com tamanho médio de 4,5 nm foi aplicada na modificação da superfície de um eletrodo de carbono vítreo (do inglês, glassy carbon electrode - GCE). O dispositivo obtido, denominado GCE/AuNPs-Si4Pic+Cl-, foi então testado como sensor eletroquímico na detecção de isômeros do nitrofenol. Através da técnica de DPV, o para-nitrofenol (p-NF) e para o orto-nitrofenol (o-NF) foram detectados separadamente e simultaneamente. Para detecção simultânea, a separação dos potenciais de pico de redução dos dois isômeros foi de 144 mV. Sob as condições otimizadas, as correntes de pico de redução de ambos os compostos aumentaram linearmente com o aumento de suas concentrações na faixa de 0,1 a 1,5 µmol L-¹. Os limites de detecção obtidos foram 43,0 nmol L-¹ e 54,0 nmol L- ¹ para o p-NF e oo-NF, respectivamente. Estes resultados indicaram que o GCE/AuNPs-Si4Pic+Cl- pode ser utilizado como sensor eletroquímico tanto para determinação individual quanto simultânea destes nitrocompostos.<br> / Abstract: This study describes the development of two different chemically modified electrodes with the 3-n-propyl-4-picolinium silsesquioxane chloride (Si4Pic+Cl-) polymer, which were applied in the selective detection of isomers of phenolic compounds. The first one, a carbon paste electrode (CPE) was modified with a water-insoluble form Si4Pic+Cl-, which was named CPE/Si4Pic+Cl-. This device was used as an electrochemical sensor for the detection of dihydroxybenzene isomers using differential pulse voltammetry (DPV). The separation between the oxidation peak potentials of hydroquinone (HQ) and catechol (CC) was large enough (114 mV) to perform a selective detection. The calibration curves were linear over the concentration range from 10.0 to 450.0 µmol L-¹ for HQ (R = 0.9983) and 10.0 to 300.0 µmol L- ¹ to CC (R = 0.9974). The limit of detection was 10.0µmol L-¹ for both isomers. In addition, the CPE/Si4Pic+Cl- exhibited good repeatability and stability, showing it is a promising electrochemical sensor for the simultaneous determination of dihydroxybenzene isomers. The second one, the water-soluble form Si4Pic+Cl- was used as a stabilizing agent for the synthesis of gold nanoparticles (AuNPs). This silsesquioxane allowed obtaining welldispersed AuNPs with an average particle size of 4.5 nm. The liquid suspension of AuNPs stabilized in Si4Pic+Cl- (AuNPs- Si4Pic+Cl-) was deposited by the drop coating method onto a glassy carbon electrode (GCE) surface to build a sensor (GCE/AuNPs-Si4Pic+Cl-) which was used for the detection of nitrophenol isomers. Through the DPV technique, o-nitrophenol (o-NP) and p-nitrophenol (p-NP) were detected individual as well as simultaneous. To simultaneous detection, the separation between the reduction peaks of isomers was 144 mV. Under optimized experimental conditions the reduction peak current increased with increasing concentrations of both nitrophenol isomers in the rangeof 0.1-1.5 µmol L-¹. The detection limits were 43.0 nmol L-¹ and 54.0nmol L-¹ for o-NP and p-NP, respectively. These findings indicate that then AuNPs-Si4Pic+Cl- material is a very promising candidate to assemble electrochemical sensors for practical applications in the field of analytical chemistry.

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