Environmental stress evaluation of Coffea arabica L. leaves from spectrophotometric fingerprints by PCA and OSC-PLS-DA

The effects of hydric stress and sunlight access conditions on metabolic compounds in coffee leaves were investigated utilizing statistical mixture design extractor solvents. PCA and OSC-PLS-DA chemometric methods were used to analyze UV-visible spectra of irrigated and non-irrigated Coffea arabica L. leaves from low (80 cm, light exposed) strata. The first latent variable of the OSC-PLS-DA score plot perfectly discriminated extracts of 34 calibration and 14 validation samples of irrigated and non-irrigated leaves. Higher spectral signals observed at the 410, 505, 535, 607 and 665 nm wavelengths are attributed to conjugate double bond pigments, mainly pheophytin a, indicating that non-irrigated conditions are more stressful than irrigated ones for this species. No significant difference was found for leaf sample extracts with varying light access conditions12842514257CAPES - Coordenação de Aperfeiçoamento de Pessoal e Nível SuperiorCNPQ - Conselho Nacional de Desenvolvimento Científico e Tecnológicosem informaçãosem informaçãoThe authors acknowledge the financial support of CNPq, CAPES, INCT – Energia e Ambiente and Fundação Araucária as well as for the scholarships granted. The Agronomic Institute of Paraná (IAPAR) is thanked for supplying the coffee leaf samples used in this wor

Respostas alimentares e arrestantes de Diabrotica speciosa a formulações contendo cucurbitacina

The objective of this work was to evaluate arrestant and stimulant feeding effects on Diabrotica speciosa (Ger.), using cucurbitacin-content starch-based formulations prepared with varying starch sources, and adding potassium lignate. In a glass slide assay, the wash off resistance of formulations was compared. Potassium lignate did not improve wash off resistance. Lagenaria vulgaris L. powder, in which cucurbitacin B concentration was determined as 0.28%, was added to the most adhesive formulation. The resultant material was used in a two-choice assay in which leaves of common bean, Phaseolus vulgaris L., treated with concentrations of 2.5%, 5%, 10%, 15% and 20% were offered to insects together with untreated control leaves. Greater number of insects and leaves consumed were found on leaves treated with cucurbitacin-content formulation (2.5%, 5% – greatest response –, 10% and 15% concentrations) than on untreated control leaves. The concentration, in which responses were higher, was sprayed in a bean field at 1,000, 1,900 and 3,000 g ha-1. Greater number of beetles was found in plots treated with the highest dosage, 3 and 6 days after spraying. Ten days after spraying, no significant differences were found among dosages, probably due to washoff of the bait.O objetivo deste trabalho foi avaliar os efeitos alimentares estimulantes e arrestantes para Diabrotica speciosa (Ger.), a partir de formulações amiláceas com cucurbitacina, variando-se as fontes de amido e adicionando-se lignato de potássio. Em ensaio com lâmina de vidro, comparou-se a resistência à lavagem das formulações. O lignato de potássio não aumentou a resistência à lavagem. Pó de Lagenaria vulgaris L., cuja concentração de cucurbitacina B foi determinada como sendo de 0,28%, foi adicionado à formulação mais adesiva. O material resultante foi utilizado em ensaios com dupla chance de escolha, nos quais folhas de feijão, Phaseolus vulgaris L., pulverizadas com concentrações de 2,5%, 5%, 10%, 15% e 20% foram oferecidas aos insetos juntamente com folhas não tratadas. Foram observados maior número de insetos e maior quantidade de folhas consumidas nas folhas tratadas com formulações com cucurbitacina (2,5%, 5% – maior resposta –, 10% e 15%) do que nas folhas não tratadas. A formulação cuja concentração teve maior resposta foi pulverizada em lavoura de feijão, nas dosagens de 1.000, 1.900 e 3.000 g ha-1. O maior número de adultos de D. speciosa foi encontrado nas parcelas tratadas com a maior dosagem, aos 3 e 6 dias após a pulverização. Dez dias após a pulverização, não foram encontradas diferenças entre as dosagens, provavelmente por causa da lavagem da isca pelas chuvas

Procedimentos analíticos para identificação de antocianinas presentes em extratos naturais

Anthocyanins are among the most important plant pigments. Due to their potential benefits for human health, there is considerable interest in these natural pigments. Nonetheless, there is great difficulty in finding a technique that could provide the identification of structurally similar compounds and estimate the number and concentration of the species present. A lot of techniques have been tried to find the best methodology to extract information from these systems. In this paper, a review of the most important procedures is given, from the extraction to the identification of anthocyanins in natural extracts

Efeito do solvente na extração de ácidos clorogênicos, cafeína e trigonelina em Coffea arabica

In this research work the effects of four solvents and their mixtures on the extraction of chlorogenic acids, caffeine and trigonelline in crude extracts of four coffee cultivars, traditional red bourbon, IAPAR59, IPR101 and IPR108 cultivars, were investigated by UV spectrophotometry and UV spectra obtained from RP-HPLC-DAD. The experimental results and the principal component analysis of UV spectra showed that the effect of solvent extraction of the metabolites does not depend on cultivars, because the spectral characteristics are similar, but the concentrations are different. The UV and UV-DAD spectra for four simplex centroid design mixtures were also similar but the concentrations of caffeine, trigonelline and the chlorogenic acids are different and depend on the solvent used in the extraction

Determination of Ni(II) in metal alloys by spectrophotometry UV-Vis using dopasemiquinone

A spectrophotometric method was proposed for Ni(II) determination in alloys using a dopa-semiquinone (L-1) to form [Ni(II)(L1-)3]1-, ε = 9.3 x 10³ L mol-1 cm-1. The optimal conditions for the determination were: wavelength 590 nm, temperature 25 °C, reaction time 45 min and pH 7.5. The Beer's law was obeyed for nickel from 3.33 x 10-5 to 1.78 x 10-4 mol L-1. The method was applied to complex samples, such as inox, nickel-titanium and cobalt-chromium alloys. A study of the potential interferents revealed that Mn was the major interferent. The limit of detection and quantification were 2.88 x 10-5 mol L-1 and 3.06 x 10-5 mol L-1, respectively

Analises espectrometricas de aguas minerais e suas classificações por meio de reconhecimento padrão

Orientador : Roy E. BrunsDissertação (mestrado) - Universidade Estadual de Campinas, Instituto de QuimicaMestrad

Desenvolvimento de um sistema quimiometrico para microcomputadores e algumas aplicações

Orientador: Roy E. BrunsTese (doutorado) - Universidade Estadual de Campinas, Instituto de QuimicaDoutorad

Uv-vis Spectral Fingerprinting And Chemometric Method Applied To The Evaluation Of Camellia Sinensis Leaves From Different Harvests

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)UV-Vis spectral fingerprinting was used to discriminate Camellia sinensis leaves of two different harvests and multivariate data analysis was applied to determine the relevant metabolites for separation. First statistical mixture designs of pure ethanol, ethyl acetate, dichloromethane and chloroform solvents as well as their binary, ternary and quaternary mixtures extracted larger varieties and amounts of C. sinensis leaf metabolites than would be obtained from classical solvent extractions. UV-Vis spectral fingerprints of crude extracts were subjected to Orthogonal Signal Correction and Partial Least Squares-Discrimination Analysis (OSC-PLS-DA) for classification. The spectra were all correctly identified and classified, showing that the OSC-PLS-DA model possesses a good predictive ability to separate spectral fingerprints of different harvests. VIP score values showed that bands at 272, 410 and 663 nm were responsible for separation. These metabolites were identified by HPLC-DAD as caffeine and pheophytin a. According to the mixture model, the maximum values of relative abundances of both caffeine and pheophytin a can be extracted with pure dichloromethane.84175377544Coordenacao de Aperfeicoamento de Pessoal de Nivel Superior (CAPES)Conselho Nacional de Desenvolvimento Cientifico e Tecnologico (CNPQ)Fundacao AraucariaCoordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq