New method for determination of (E)resveratrol in wine based on microextraction using packed sorbent and ultra-performance liquid chromatography

An ultra-fast and improved analytical methodology based on microextraction by packed sorbent (MEPS) combined with ultra-performance LC (UPLC) was developed and validated for determination of (E)-resveratrol in wines. Important factors affecting the performance of MEPS such as the type of sorbent material (C2, C8, C18, SIL, and M1), number of extraction cycles, and sample volume were studied. The optimal conditions of MEPS extraction were obtained using C8 sorbent and small sample volumes (50���250mL) in one extraction cycle (extract���discard) and in a short time period (about 3 min for the entire sample preparation step). (E)-Resveratrol was eluted by 1 250mL of the mixture containing 95% methanol and 5% water, and the separation was carried out on a highstrength silica HSS T3 analytical column (100 mm 2.1 mm, 1.8mm particle size) using a binary mobile phase composed of aqueous 0.1% formic acid (eluent A) and methanol (eluent B) in the gradient elution mode (10 min of total analysis). The method was fully validated in terms of linearity, detection (LOD) and quanti���cation (LOQ) limits, extraction yield, accuracy, and inter/intra-day precision, using a Madeira wine sample (ET) spiked with (E)-resveratrol at concentration levels ranging from 5 to 60mg/mL. Validation experiments revealed very good recovery rate of 9575.8% RSD, good linearity with r2 values 40.999 within the established concentration range, excellent repeatability (0.52%), and reproducibility (1.67%) values (expressed as RSD), thus demonstrating the robustness and accuracy of the MEPSC8/UPLC-photodiode array (PDA) method. The LOD of the method was 0.21mg/mL, whereas the LOQ was 0.68mg/mL. The validated methodology was applied to 30 commercial wines (24 red wines and six white wines) from different grape varieties, vintages, and regions. On the basis of the analytical validation, the MEPSC8/UPLC-PDA methodology shows to be an improved, sensitive, and ultra-fast approach for determination of (E)-resveratrol in wines with high resolving power within 6 min.

Pr��ticas e comportamentos de lideran��a na gest��o dos recursos humanos escolares: estudo de caso numa escola da Regi��o Aut��noma da Madeira

Num mundo globalizado e complexo em que o capital humano assume centralidade em tem��ticas associadas �� lideran��a das organiza����es e consequente gest��o de recursos humanos, em termos escolares, urge perceber que percep����es t��m os liderados, pessoal docente e n��o docente, acerca das pr��ticas e comportamentos da lideran��a. O estudo compreendeu uma fase explorat��ria que envolveu a pesquisa de teorias e trabalhos desenvolvidos, nomeadamente, monografias, livros, teses e artigos, de forma a construir-se um quadro te��rico de refer��ncia acerca da gest��o de recursos humanos e da lideran��a. O modelo de orienta����o privilegiado foi o das ���5 Pr��ticas da Lideran��a Exemplar��� de Kouzes e Posner (2009). A investiga����o, de natureza quantitativa e qualitativa, privilegiou como estrat��gia de pesquisa o estudo de caso, incidindo sobre uma Escola B��sica dos 2�� e 3�� Ciclos da Regi��o Aut��noma da Madeira. Como instrumentos de recolha de dados, foram utilizados a an��lise de conte��do e o inqu��rito por question��rio. Foi administrado, ao pessoal docente e n��o docente da escola, o question��rio LPI - Observer (Leadership Practice Inventory) desenvolvido por Kouzes e Posner (2003b). A an��lise de conte��do recaiu sobre dois documentos da escola, a saber, o Projecto Educativo de Escola e o Plano Anual de Escola. Conclu��mos que, na opini��o dos inquiridos, as pr��ticas de lideran��a que dever��o ser privilegiadas por um l��der eficaz s��o ���Permitir que os outros ajam��� e ���Encorajar a vontade���. Os inquiridos consideram que o l��der adopta pr��ticas de uma lideran��a exemplar, no entanto, a sua frequ��ncia �� inferior ��s que dever��o ser observadas num l��der eficaz. A pr��tica mais frequentemente observada, no l��der, �� ���Permitir que os outros ajam���. Por ��ltimo, por categoria, verificou-se que �� o Pessoal Docente que percepciona mais frequentemente comportamentos de lideran��a exemplar no l��der.

HPLC-DAD methodology for the quanti���cation of organic acids, furans and polyphenols by direct injection of wine samples

This article proposes a simple and sensitive HPLC method with photo-diode array detection for the analysis of organic acids, monomeric polyphenols and furanic compounds in wine samples by direct injection. The chromatographic separation of 8 organic acids, 2 furans and 22 phenolic compounds was carried out with a buffered solution (pH 2.70) and acetonitrile as mobile phases and a difunctionally bonded C18 stationary phase, Atlantis dC18 (250 4.6 mm, 5mm) column. The elution was performed in 12 min for the organic acids and in 60 min for the phenolic compounds, including phenolic acids, stilbenes and ���avonoids. Target compounds were detected at 210 nm (organic acids, ���avan-3-ols and benzoic acids), 254 nm (ellagic acid), 280 nm (furans and cinnamic acid), 315 nm (hydroxycinnamic acids and trans-resveratrol) and 360 nm (���avonoids). The RSD for the repeatability test (n55) of peak area and retention times were below 3.1 and 0.3%, respectively, for phenolics and below 1.0 and 0.2% for organic acids. The RSDs expressing the reproducibility of the method were higher than for the repeatability results but all below 9.0%. Method accuracy was evaluated by the recovery results, with averaged values between 80 and 104% for polyphenols and 97���105% for organic acids. The calibration curves, obtained by triplicate injection of standard solutions, showed good linearity with regression coef���cients higher than 0.9982 for polyphenols and 0.9997 for organic acids. The LOD was in the range of 0.07���0.49 mg/L for polyphenols (cinnamic and gallic acids, respectively) and 0.001���0.046 g/L for organic acids (oxalic and lactic acids, respectively). The method was successfully used to measure and assess the polyphenolic ���ngerprint and organic acids pro���le of red, white, rose �� and forti���ed wines.

Phenolic profile of Sercial and Tinta Negra Vitis vinifera L. grape skins by HPLC���DAD���ESI-MSn: novel phenolic compounds in Vitis vinifera L. grape

This study represents the first phytochemical research of phenolic components of Sercial and Tinta Negra Vitis vinifera L. The phenolic profiles of Sercial and Tinta Negra V. vinifera L. grape skins (white and red varieties, respectively) were established using high performance liquid chromatography���diode array detection���electrospray ionisation tandem mass spectrometry (HPLC���DAD���ESI-MSn), at different ripening stages (v��raison and maturity). A total of 40 phenolic compounds were identified, which included 3 hydroxybenzoic acids, 8 hydroxycinnamic acids, 4 flavanols, 5 flavanones, 8 flavonols, 4 stilbenes, and 8 anthocyanins. For the white variety, in both ripening stages, hydroxycinnamic acids and flavonols were the main phenolic classes, representing about 80% of the phenolic composition. For red variety, at v��raison, hydroxycinnamic acids and flavonols were also the predominant classes (71%), but at maturity, anthocyanins represented 84% of the phenolic composition. As far as we know, 10 compounds were reported for the first time in V. vinifera L. grapes, namely protocatechuic acid-glucoside, p-hydroxybenzoyl glucoside, caftaric acid vanilloyl pentoside, p-coumaric acid-erythroside, naringenin hexose derivate, eriodictyol-glucoside, taxifolin-pentoside, quercetin-glucuronide-glucoside, malylated kaempferol-glucoside, and resveratrol dimer. These novel V. vinifera L. grape components were identified based on their MSn fragmentation profile. This data represents valuable information that may be useful to oenological management and to valorise these varieties as sources of bioactive compounds.

A new and improved strategy combining a dispersive-solid phase extraction-based multiclass method with ultra high pressure liquid chromatography for analysis of low molecular weight polyphenols in vegetables

This paper reports on the development and optimization of a modified Quick, Easy, Cheap Effective, Rugged and Safe (QuEChERS) based extraction technique coupled with a clean-up dispersive-solid phase extraction (dSPE) as a new, reliable and powerful strategy to enhance the extraction efficiency of free low molecular-weight polyphenols in selected species of dietary vegetables. The process involves two simple steps. First, the homogenized samples are extracted and partitioned using an organic solvent and salt solution. Then, the supernatant is further extracted and cleaned using a dSPE technique. Final clear extracts of vegetables were concentrated under vacuum to near dryness and taken up into initial mobile phase (0.1% formic acid and 20% methanol). The separation and quantification of free low molecular weight polyphenols from the vegetable extracts was achieved by ultrahigh pressure liquid chromatography (UHPLC) equipped with a phodiode array (PDA) detection system and a Trifunctional High Strength Silica capillary analytical column (HSS T3), specially designed for polar compounds. The performance of the method was assessed by studying the selectivity, linear dynamic range, the limit of detection (LOD) and limit of quantification (LOQ), precision, trueness, and matrix effects. The validation parameters of the method showed satisfactory figures of merit. Good linearity (View the MathML sourceRvalues2>0.954; (+)-catechin in carrot samples) was achieved at the studied concentration range. Reproducibility was better than 3%. Consistent recoveries of polyphenols ranging from 78.4 to 99.9% were observed when all target vegetable samples were spiked at two concentration levels, with relative standard deviations (RSDs, n = 5) lower than 2.9%. The LODs and the LOQs ranged from 0.005 ��g mL���1 (trans-resveratrol, carrot) to 0.62 ��g mL���1 (syringic acid, garlic) and from 0.016 ��g mL���1 (trans-resveratrol, carrot) to 0.87 ��g mL���1 ((+)-catechin, carrot) depending on the compound. The method was applied for studying the occurrence of free low molecular weight polyphenols in eight selected dietary vegetables (broccoli, tomato, carrot, garlic, onion, red pepper, green pepper and beetroot), providing a valuable and promising tool for food quality evaluation.

A fast method using a new hydrophilic���lipophilic balanced sorbent in combination with ultra-high performance liquid chromatography for quantification of significant bioactive metabolites in wines

This manuscript describes the development and validation of an ultra-fast, efficient, and high throughput analytical method based on ultra-high performance liquid chromatography (UHPLC) equipped with a photodiode array (PDA) detection system, for the simultaneous analysis of fifteen bioactive metabolites: gallic acid, protocatechuic acid, (���)-catechin, gentisic acid, (���)-epicatechin, syringic acid, p-coumaric acid, ferulic acid, m-coumaric acid, rutin, trans-resveratrol, myricetin, quercetin, cinnamic acid and kaempferol, in wines. A 50-mm column packed with 1.7-��m particles operating at elevated pressure (UHPLC strategy) was selected to attain ultra-fast analysis and highly efficient separations. In order to reduce the complexity of wine extract and improve the recovery efficiency, a reverse-phase solid-phase extraction (SPE) procedure using as sorbent a new macroporous copolymer made from a balanced ratio of two monomers, the lipophilic divinylbenzene and the hydrophilic N-vinylpyrrolidone (Oasis��� HLB), was performed prior to UHPLC���PDA analysis. The calibration curves of bioactive metabolites showed good linearity within the established range. Limits of detection (LOD) and quantification (LOQ) ranged from 0.006 ��g mL���1 to 0.58 ��g mL���1, and from 0.019 ��g mL���1 to 1.94 ��g mL���1, for gallic and gentisic acids, respectively. The average recoveries �� SD for the three levels of concentration tested (n = 9) in red and white wines were, respectively, 89 �� 3% and 90 �� 2%. The repeatability expressed as relative standard deviation (RSD) was below 10% for all the metabolites assayed. The validated method was then applied to red and white wines from different geographical origins (Azores, Canary and Madeira Islands). The most abundant component in the analysed red wines was (���)-epicatechin followed by (���)-catechin and rutin, whereas in white wines syringic and p-coumaric acids were found the major phenolic metabolites. The method was completely validated, providing a sensitive analysis for bioactive phenolic metabolites detection and showing satisfactory data for all the parameters tested. Moreover, was revealed as an ultra-fast approach allowing the separation of the fifteen bioactive metabolites investigated with high resolution power within 5 min.

Quantification of polyphenols with potential antioxidant properties in wines using reverse phase HPLC

A RP-HPLC method with photodiode array detection (DAD) was developed to separate, identify and quantify simultaneously the most representative phenolic compounds present in Madeira and Canary Islands wines. The optimized chromatographic method was carefully validated in terms of linearity, precision, accuracy and sensitivity. A high repeatability and a good stability of phenolics retention times (a3%) were obtained, as well as relative peak area. Also high recoveries were achieved, over 80.3%. Polyphenols calibration curves showed a good linearity (r2 A0.994) within test ranges. Detection limits ranged between 0.03 and 11.5 lg/mL for the different polyphenols. A good repeatability was obtained, with intra-day variations less than 7.9%. The described method was successfully applied to quantify several polyphenols in 26 samples of different kinds of wine (red, ros and white wines) from Madeira and Canary Islands. Gallic acid was by far the most predominant acid. It represents more than 65% of all phenolics, followed by p-coumaric and caffeic acids. The major flavonoid found in Madeira wines was trans-resveratrol. In some wines, (���)-epicatechin was also found in highest amount. Canary wines were shown to be rich in gallic, caffeic and p-coumaric acids and quercetin.

Universidade inclusiva e o aluno com necessidades especiais: a investiga����o realizada em Portugal

A presente investiga����o tem como objetivo principal contribuir para a reflex��o e sensibiliza����o das NEE no Ensino Superior, atrav��s da sistematiza����o da investiga����o cient��fica realizada em Portugal, nos ��ltimos anos. Pretende-se, assim, contribuir para um maior conhecimento desta realidade no nosso pa��s. Para o efeito, procedeu-se a um levantamento bibliogr��fico dos documentos dispon��veis na ��rea das NEE no ES em tr��s bases de dados: RCAAP (Reposit��rio Cient��fico de Acesso Aberto em Portugal); B-On (Biblioteca de Conhecimento Online) e o motor de busca Google. Ap��s a consulta das bases de dados, foram encontrados trinta e cinco documentos, distribu��dos em oito Teses (seis Teses de Mestrado e duas Teses de Doutoramento), onze artigos em Revista (dez artigos em Revista Nacional e um artigo em Revista Internacional), quinze Documentos em Confer��ncia e um Cap��tulo de Livro. Os dados recolhidos permitem perceber que, paulatinamente, a quest��o das NEE no Ensino Superior tem despertado o interesse dos investigadores, sendo uma ��rea onde a possibilidade e necessidade de mais estudos �� uma realidade.