Documents disponibles écrits par cet auteur

Comparative study of solid - phase extraction and liquid − liquid extraction for the reliable quantification of high value added compounds from oxidation processes of wood - derived lignin / Paula C. Rodrigues Pinto in Industrial & engineering chemistry research, Vol. 49 N° 23 (Décembre 2010) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 49 N° 23 (Décembre 2010) . - pp. 12311–12318 Titre : Comparative study of solid - phase extraction and liquid − liquid extraction for the reliable quantification of high value added compounds from oxidation processes of wood - derived lignin Type de document : texte imprimé Auteurs : Paula C. Rodrigues Pinto, Auteur ; Eduardo A. Borges da Silva, Auteur ; Alirio Egidio Rodrigues, Auteur Année de publication : 2011 Article en page(s) : pp. 12311–12318 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : Solid  phase  Liquid  Oxidation  processes Résumé : Technologies and processes for lignocellulosic conversion in biorefineries are emergent subjects of research for which a reliable analysis of raw materials and quantification of yields of reaction products are required. This paper presents the development of an analytical method, using solid-phase extraction (SPE), for application to the reaction mixture of the oxidation of wood-derived lignin. The aim of the method is to extract the high value added aldehydes for quantification by high-performance liquid chromatography with ultraviolet detection (HPLC-UV). SPE and conventional liquid−liquid extraction (LLE) were evaluated and compared concerning recoveries and precision: (i) solutions of standard phenolic compounds (in alkaline medium and in lignin as matrix) and (ii) real samples and spiked real samples. The presence of lignin in the solutions decreases the recoveries of compounds from about 100% (no lignin) to 91% (for prepared solutions of lignin) and 94% (for real samples). This decrease was clearly evident with the increase of concentration of phenolic compounds in spiked real samples. The recovery averages and precision of SPE were higher than those of LLE and less affected by the presence of lignin. The results gathered and discussed in this work revealed SPE as an alternative to LLE: it is less time-consuming and has higher accuracy and precision for the quantification of phenolic compounds as reaction products of lignin oxidation. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie101680s [article] Comparative study of solid - phase extraction and liquid − liquid extraction for the reliable quantification of high value added compounds from oxidation processes of wood - derived lignin [texte imprimé] / Paula C. Rodrigues Pinto, Auteur ; Eduardo A. Borges da Silva, Auteur ; Alirio Egidio Rodrigues, Auteur . - 2011 . - pp. 12311–12318. Chimie industrielle Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 49 N° 23 (Décembre 2010) . - pp. 12311–12318 Mots-clés : Solid  phase  Liquid  Oxidation  processes Résumé : Technologies and processes for lignocellulosic conversion in biorefineries are emergent subjects of research for which a reliable analysis of raw materials and quantification of yields of reaction products are required. This paper presents the development of an analytical method, using solid-phase extraction (SPE), for application to the reaction mixture of the oxidation of wood-derived lignin. The aim of the method is to extract the high value added aldehydes for quantification by high-performance liquid chromatography with ultraviolet detection (HPLC-UV). SPE and conventional liquid−liquid extraction (LLE) were evaluated and compared concerning recoveries and precision: (i) solutions of standard phenolic compounds (in alkaline medium and in lignin as matrix) and (ii) real samples and spiked real samples. The presence of lignin in the solutions decreases the recoveries of compounds from about 100% (no lignin) to 91% (for prepared solutions of lignin) and 94% (for real samples). This decrease was clearly evident with the increase of concentration of phenolic compounds in spiked real samples. The recovery averages and precision of SPE were higher than those of LLE and less affected by the presence of lignin. The results gathered and discussed in this work revealed SPE as an alternative to LLE: it is less time-consuming and has higher accuracy and precision for the quantification of phenolic compounds as reaction products of lignin oxidation. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie101680s

Extraction of Polyphenolic Compounds from Eucalyptus globulus Bark / Inês Mota in Industrial & engineering chemistry research, Vol. 51 N° 20 (Mai 2012) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 51 N° 20 (Mai 2012) . - pp. 6991-7000 Titre : Extraction of Polyphenolic Compounds from Eucalyptus globulus Bark : Process Optimization and Screening for Biological Activity Type de document : texte imprimé Auteurs : Inês Mota, Auteur ; Paula C. Rodrigues Pinto, Auteur ; Catarina Novo, Auteur Année de publication : 2012 Article en page(s) : pp. 6991-7000 Note générale : Industrial chemistry Langues : Anglais (eng) Mots-clés : Biological  activity  Optimization  Bark Résumé : The bark of Eucalyptus globulus is a promising source of polyphenolic compounds that could be extracted employing polar solvents. Extraction experiments were planned according to the Box-Behnken design to evaluate the effect of temperature and time of extraction and the ethanol/water ratio on the dependent variables total phenolic content (TPC; as gallic acid equivalents, GAE), antioxidant activity (AA; as millimoles of ascorbic acid equivalents, AAE), proanthocyanidins (Pac; as mimosa extract equivalents, MEE), Stiasny number (SN), and coextracted total carbohydrates (TC). Response surface models were developed, and statistical analysis of variance was performed. A maximum of TPC of 32% (wGAE/wextract) was achieved for 264 min, 82.5 °C, and 52% ethanol corresponding to about 2% of the bark weight. These conditions are close to those leading to maximum values of compounds with AA (2.1 mmolAAE/gextract) and Pac 14% (wMEE/wextract). TC in the extract and the SN predicted were 22.7% (wTC/wextract) and 37, respectively. Preliminary studies concerning the biological activity of some extracts have demonstrated their differential capacity to reduce human breast cancer cell proliferation. ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=25925040 [article] Extraction of Polyphenolic Compounds from Eucalyptus globulus Bark : Process Optimization and Screening for Biological Activity [texte imprimé] / Inês Mota, Auteur ; Paula C. Rodrigues Pinto, Auteur ; Catarina Novo, Auteur . - 2012 . - pp. 6991-7000. Industrial chemistry Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 51 N° 20 (Mai 2012) . - pp. 6991-7000 Mots-clés : Biological  activity  Optimization  Bark Résumé : The bark of Eucalyptus globulus is a promising source of polyphenolic compounds that could be extracted employing polar solvents. Extraction experiments were planned according to the Box-Behnken design to evaluate the effect of temperature and time of extraction and the ethanol/water ratio on the dependent variables total phenolic content (TPC; as gallic acid equivalents, GAE), antioxidant activity (AA; as millimoles of ascorbic acid equivalents, AAE), proanthocyanidins (Pac; as mimosa extract equivalents, MEE), Stiasny number (SN), and coextracted total carbohydrates (TC). Response surface models were developed, and statistical analysis of variance was performed. A maximum of TPC of 32% (wGAE/wextract) was achieved for 264 min, 82.5 °C, and 52% ethanol corresponding to about 2% of the bark weight. These conditions are close to those leading to maximum values of compounds with AA (2.1 mmolAAE/gextract) and Pac 14% (wMEE/wextract). TC in the extract and the SN predicted were 22.7% (wTC/wextract) and 37, respectively. Preliminary studies concerning the biological activity of some extracts have demonstrated their differential capacity to reduce human breast cancer cell proliferation. ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=25925040