Publish in OALib Journal

ISSN: 2333-9721

APC: Only $99


Any time

2019 ( 19 )

2018 ( 105 )

2017 ( 130 )

2016 ( 147 )

Custom range...

Search Results: 1 - 10 of 4552 matches for " Chromatography "
All listed articles are free for downloading (OA Articles)
Page 1 /4552
Display every page Item
Volatile Components in the Flower, Pedicellate Ovary and Aqueous Residue of Cymbidium sp. (ORCHIDACEAE)  [PDF]
Víctor García Gaytán, María de las Nieves Rodríguez Mendoza, Marcos Soto Hernández, Libia I. Trejo-Téllez, Martha E. Pedraza Santos, Guadalupe Valdovinos Ponce
Journal of Analytical Sciences, Methods and Instrumentation (JASMI) , 2013, DOI: 10.4236/jasmi.2013.34027

Cymbidium sp. has several ornamental, medicinal and cosmetic uses. Essential oils were obtained through extraction by hydrodistillation of flower and pedicellate ovary. The chromatographic profile was obtained by thin layer chromatography (TLC), combined with gas chromatography-mass spectrometry (GC/MS), for the identification and relative quantification of various substances in three samples from the orchid (flower, pedicellate ovary and aqueous residue). With TLC, five compounds were identified in the flower, with the most abundant being terpineol, linalool and zingiberene, and five in the pedicellate ovary, with borneol, cineole, and β-bisabolene being in the greatest concentration, while for the aqueous residue, the most abundant was geraniol. Using GC/MS, 25 volatile components associated with the flower were identified, of which the most abundant were linalool (22.92%), 4-methyl-phenol (15.07%) and p-Menth-1-en-8-ol (12.32%). In pedicellate ovaries, 13 components were identified, with the most abundant being 4-methyl-phenol (31.24%), bicycle [4.4.0] dec-1-ene, 2-isopropyl-5-methyl-9-methylene-(17.74%) and 2-hexanone (10.24%), while in the aqueous residue 18 components were found, with the most abundant being 4-methyl-phenol (18.71%) and 2- cyclohexen-1-ol (14.60%).

Chromatographic Separation and Characterization of Capsaicinoids and Their Analogues  [PDF]
Jun-lian Wang, Li Zhou, Lei Wang, Zheng hong Peng, Sheng ze Zhou, Xiang feng Zhou, Xiao bin Zhang, Bixian Peng
Pharmacology & Pharmacy (PP) , 2011, DOI: 10.4236/pp.2011.23018
Abstract: An attempt was made to establish a chromatographic separation and analysis method for capsaicinoids and their analogues. A series of factors,such as choice of column and eluents, eluent composition,flow rate of eluent and operational temperature were correlated, countereacted and optimized to attain appropriate separation efficiency and finalize the experimentally oprational procedures as a whole, permiting a mixture comprising 8 capsaicinoids including analogues to be separated and Characterized with an allowed deviations and within a period of 36 minutes via 1 test as well.
Contribution to the Study of Phytosterols and Phenolics from the Barks and Leaves of the Trichilia Catigua A. Juss., Meliaceae  [PDF]
Jessé Boquett Lagos, Carlos Alberto Bruel Gemin, Josiane de Fátima Gaspari Dias, Marilis Dallarmi Miguel, Ranieri Campos, Jo?o Luiz de Souza Carvalho, Márcia do Rocio Duarte, Obdulio Gomes Miguel
Journal of Analytical Sciences, Methods and Instrumentation (JASMI) , 2012, DOI: 10.4236/jasmi.2012.21008
Abstract: Trichilia catigua is a Brazilian native species known as \"catuaba”. This study investigated the chromatographic features hydroalcoholic extracts that were obtained by different techniques, from barks and leaves. The chromatographic analysis has demonstrated the presence of chlorogenic acid, epicathechin and cathechin, as well as the presence of β-sitosterol and stigmasterol in both analyzed plant parts. The best results were those when it was used turbo-extraction, extraction using Soxhlet apparatus and ethanol 50%.
Morphological and chemical aspects of Chlorella pyrenoidosa, Dunaliella tertiolecta, Isochrysis galbana and Tetraselmis gracilis microalgae  [PDF]
Cristiane Mesquita da Silva Gorg?nio, Donato Alexandre Gomes Aranda, S?nia Couri
Natural Science (NS) , 2013, DOI: 10.4236/ns.2013.57094

This study evaluates the growth and chemical composition of the following marine microalgae: Dunaliella tertiolecta, Isochrysis galbana, and Tetraselmis gracilis and the chemical composition of Chlorella pyrenoidosa. Microalgae can produce a number of compounds of high commercial value for the industry, mainly for the food industry. The growth kinetics, cell volume, pigments, carbohydrates, proteins, lipids, and fatty acid and amino acid composition were evaluated. I. galbana had the largest number of cells per mL-1 (107), concentration of carotenoids (6.33 μg·mL-1), and carbohydrates (34.32%). D. tertiolecta and T. gracilis had the highest cell volume (560.6 and 592.7 μm3, respectively), the highest amount of total dry biomass. D. tertiolecta

Structure Elucidation of a New Toxin from the Mushroom Cortinarius rubellus Using Gas Chromatography-Mass Spectrometry (GC-MS)  [PDF]
Ilia Brondz
International Journal of Analytical Mass Spectrometry and Chromatography (IJAMSC) , 2013, DOI: 10.4236/ijamsc.2013.12014

Cortinarius orellanus (Fries) and C. rubellus (Cooke),which were formerly also known as C. speciosissimus, are poisonous mushrooms containing the toxin orellanine and several degradation products of orellanine,includingorelline and orellinine. Mass intoxication by poisonous mushrooms was observed in Poland in 1952-1957 [1]. In 1957, the cause of these outbreaks was described by Grzymala as poisoning by a member of the Cortinarius family. The toxin orellanine was first isolated from C. orellanusby Grzymala in 1962; the chemical structure of orellanine was later determined to be 3,3',4,4'-tetrahydroxy-2,2'-bipyridine-N,N'-dioxide. Poisoning with C. orellanus and C. rubellus has a very specific character. The first symptoms of intoxication usually do not appear until 2-3 days after ingestion, but in some cases intoxication appears after three weeks. The target organ for the toxin is the kidney. Histologically, it is easy to record the specific damage. The presence of degradation products of orellanine in kidney can be confirmed chromatographically, suggesting that the cause of poisoning is orellanine. However, the presence of orellanine in the blood of intoxicated persons has not been directly detected. A specific model was developed by Brondz et al. for the detection of orellanine, orelline, and orellininein animal stomach fluids [2-4]. The hypothesis that the fungal toxin orellanine as a diglucoside can be transported from the digestive system by the blood to the kidney could not be supported. The toxin orellanine as a diglucoside is very unstable in an aqueous acidic environment.[i1] However, in the present study, it was possible to record an additional substance in animal stomach fluids using GC-MSafter ingestion ofC. rubellus. This substance, which has been namedrubelline, is part of a toxic mixture inC. orellanusandC. rubellusand is closely related to orellanine. The structure of rubelline is more suitable than orellanine for absorptionfromthe digestive tract and for transport in the blood. The presented hypothesis is that rubellineis absorbed in the digestive tract and transportedin the blood to the kidney, where it is biotransformed to orellanine and accumulatedto toxic levels. The process of biotransformationis in itself also

Replacement of Process Scale Chromatography by Counterflow Membrane Cascades  [PDF]
Edwin N. Lightfoot, Bar?? ünal
Advances in Bioscience and Biotechnology (ABB) , 2014, DOI: 10.4236/abb.2014.511106
Abstract: Invention and innovation, always important, become ever more so in these fast changing and competitive times. They are in addition primarily dependent upon the dynamic behavior of the human mind. Our underlying purpose here is to examine these creative processes and to provide means to make them more effective. This is a timely effort because our understanding of perception and its interpretation by the human brain is very rapidly advancing. Even experimental insights into mental activity can be determined with rapidly increasing effectiveness. The framework of our discussion is that of evolution dynamics, and the scientific bases are rapidly developing neural sciences. However the bulk of our discussion deals with a specific example: the replacement of process scale chromatography by membrane-mediated steady counterflow in downstream processing. We do this because inventive activities must depend upon intimate knowledge of the systems available.
Comparative Analysis and Validation Methodologies of GC and HPLC for Analysis of Cholesterol in Meat Products  [PDF]
Gisely Luzia Stroher, Angela Claudia Rodrigues, Lucia Felicidade Dias, Mayka Reghiany Pedr?o, Luana Nascimento de Paula, Jesui Vergilio Visentainer, Nilson Evelazio de Souza
American Journal of Analytical Chemistry (AJAC) , 2012, DOI: 10.4236/ajac.2012.34042
Abstract: This study validated different extraction methodologies and compared the quantification of cholesterol by gas chromatography (GC) and high performance liquid chromatography (HPLC) in mg per 100 g of Italian-type salami and traditional bologna. The GC method used was direct saponification of the samples without derivatizations and the HPLC method was used to extract of the lipid samples. The GC limits of detection and quantification obtained for cholesterol were, respectively, 0.001 and 0.003 mg.g–1. The HPLC values were 0.005 mg.g–1 and 0.016 mg.g–1. The GC recovery rate was 97.10 ± 0.13 and that of HPLC was 93.33 ± 0.22. Comparison of the cholesterol quantity found using the two chromatographic techniques shows that both are capable of quantifying cholesterol in the foods. With regard to costs, analysis time, the cost/benefit relationship was better with gas chromatography than that obtained with high performance liquid chromatography.
Investigation of Yield Regulation of Red Grapes on the Concentration of Some Crucial Wine Components  [PDF]
Kinga K. Rácz, Miklós Kállay, Nóra Bakos-Barczi, László Rácz, Csaba Csutorás
Agricultural Sciences (AS) , 2016, DOI: 10.4236/as.2016.74027
Abstract: An essential concept of making quality wine is that the quality comes from the vineyard. The dissolved materials and components determine the value of wine. Their amount and proportion are essentially influenced by grape variety, terroir, the way of cultivation, weather conditions, grape quality, the time of vintage and the method of grape and wine processing. In the present study the effect on wine quality of different ways of yield regulations was examined in wines of three consecutive years. Besides basic parameters, total polyphenol and resveratrol contents were determined in wines of Blaufr?nkisch and Merlot varieties. Our measurements were carried out by spectrophotometry, gas and liquid chromatography. Our investigations confirmed that yield regulation led to increased extract content and outstanding quality of the produced wine.
Arsenic Speciation Analysis by Ion Chromatography - A Critical Review of Principles and Applications  [PDF]
Adrian A. Ammann
American Journal of Analytical Chemistry (AJAC) , 2011, DOI: 10.4236/ajac.2011.21004
Abstract: Multiple acute and chronic toxicity of arsenic species and its mobilisation from geological deposits into ground and drinking water resources is one of the greatest threats to human health. Arsenic speciation analy-sis, mostly done by liquid chromatography, is a challenging task which requires an intense high quality work with respect to extraction, preservation, separation, detection and validation. A growing number of As-spe-cies and low regulatory limits (10 μg/L) may require more than one speciation method preferably performed by species specific procedures and detectors. Beside As-fractionation for special application there are many selective speciation methods based on high performance separation techniques like capillary electrophoreses, gas and liquid chromatography. Both, fractionation and speciation methods are reviewed. However, the focus is on scopes and limits of ion chromatographic separations, the most frequently used methods. Based on IC-principles the methods applied are critically discussed and recommendations given which should result in more robust and reliable As-speciation.
Use of SFC in Extraction of Adaptogens from Brazilian Plants  [PDF]
Marcelle Fernanda Carulo
American Journal of Analytical Chemistry (AJAC) , 2012, DOI: 10.4236/ajac.2012.312A129

Bioactive substances found in plants are very interesting because of their importance in medicine and foods. Species of Pfaffia genre is common in Brazil, the largest center of collection of this species. Statistics report that 11,000 tons of roots and other plants were exported in 2011. Due to the large market demand, a growth of 10% per year is estimated. One of the promising areas of study involves the supercritical fluid extraction of active compounds present in plants. The current goal is to reduce dependence on foreign markets. The extraction of bioactive compound known as Beta-Ecdysone has been studied. Statistics show that profits of exports coming from the raw material is almost ten times smaller than the extract itself. Considering this fact, we emphasize the importance of an alternative method of industrial extraction in Brazil using supercritical technology, which proves to be environmentally safe.

Page 1 /4552
Display every page Item

Copyright © 2008-2017 Open Access Library. All rights reserved.