Search results for "ethanol"
showing 10 items of 2041 documents
Organochlorine residue analysis of commercial milks by capillary gas chromatography
1991
The determination of organochlorine pesticides and polychlorinated biphenyls in milks requires the use of efficient extraction methods. A rapid procedure has been developed, based on extraction of organochlorine residues from milk on to octadecylsilica solid phase extraction cartridges and elution with hexane. The addition of different organic solvents to the milk before solid phase extraction has been studied. The use of methanol to disrupt the fat globules enables almost complete recovery of the residues with minimum extraction of fatty substances. Recovery experiments were performed for eighteen compounds present at ppb levels in whole, two per cent, and skimmed milks. The average recove…
Photochemical derivatization and fluorimetric determination of reserpine in a flow-injection assembly
1991
Abstract The fluorimetric flow-injection determination of reserpine was achieved with the drug being derivatized on-line by photoreaction. PTFE tubing was helically coiled around a germicide lamp located between the injection valve and detector. Two analytical procedures are proposed using either dilute acetic acid or pure methanol as the carrier stream. The influence of foreign compounds was studied and the method was applied to the determination of reserpine in pharmaceutical formulations.
Lipid hydroperoxides determination in milk‐based infant formulae by gas chromatography
2003
A simple gas chromatograph using a flame ionization detector and a polar capillary column method is proposed for determining hydroperoxides in the lipid fraction of milkbased infant formulas. Tricosanoic acid is used as internal standard. The method includes the following steps: a) the extraction of fat with chloroform/methanol (2:1, v/v), b) the reduction of hydroperoxide acids to hydroxide acids with hydrogen gas and palladium as a catalyst, c) the transmethylation to obtain the methyl esters with acetyl chloride and methanol/ hexane (4:1, v/v), and d) an acetylation with acetic anhydride/ pyridine (4:1, v/v) to obtain an acetoxy derivate of the hydroxide present. Two chromatography runs,…
Isobaric Vapor–Liquid–Liquid Equilibria for the Ternary Systems Ethanol + Water + Propyl Acetate and 1-Propanol + Water + Propyl acetate
2014
In order to break azeotropes appearing in mixtures of water and either ethanol or 1-propanol, an azeotropic distillation process is proposed using propyl acetate as entrainer. Therefore, isobaric vapor–liquid–liquid equilibrium (VLLE) data at atmospheric pressure have been obtained for the ternary systems ethanol + water + propyl acetate and 1-propanol + water + propyl acetate. Data correlation has been carried out in four different ways and a comparison between the results obtained in each correlation has been done. The set of parameters obtained from the best correlation has been used in the VLLE estimation. Effects of using propyl acetate as entrainer in the azeotropic distillation have …
High-pressure solubility data of system ethanol (1)+catechin (2)+CO2 (3)
2001
Abstract Supercritical fluid extraction posses several advantages over traditional liquid–solvent-based extraction methods including improved selectivity, expeditiousness, automation and environmental safety. Fluid phase equilibrium data is essential for study the viability of supercritical extraction and the design of the extraction columns often used for this type of separations. During the past few years it has been demonstrated that phenolic compounds, such catechins and procyanidins from seeds, contribute to both the flavour properties and the pharmacological effects of wine. The extraction of catechin using supercritical CO2 is not possible, it only extracts traces of product, probabl…
High-pressure solubility data of the system resveratrol (3)+ethanol (2)+CO2 (1)
2001
Abstract Supercritical fluid extraction possesses several advantages over traditional liquid-solvent-based extraction methods, including improved selectivity, expeditiousness, automation and environmental safety. Fluid-phase equilibrium data are essential for studying the viability of supercritical extraction and the design of the extraction columns often used for this type of separation. Resveratrol has been correlated with serum lipid reduction and inhibition of platelet aggregation, and its cancer chemopreventive activity has recently been reported. The extraction of resveratrol using supercritical CO 2 is not possible; it only extracts traces of product, probably due to its polar nature…
Effect of ethanol on yeast film formation
1999
<p style="text-align: justify;">In this study, we have investigated the influence of ethanol on yeast film formation and cell surface hydrophobicity (CSH). A yeast strain (P3) previously isolated from film yeast was grown in a medium containing increasing ethanol concentration ranging from 0 to 14 p. cent (v/v). It results from this study that up to 10 p. cent ethanol, the greater was the ethanol concentration, the greater was the growth of film. Using two different techniques (phase partition method, magnobead assay), we have shown that ethanol altered the CSH of the yeast. The measured hydrophobicity (p. cent) of cells grown without ethanol was 65 p. cent compared with 81 p. cent wi…
Levan-ethanol biosynthesis using Zymomonas mobilis cells immobilized by attachment and entrapment
2001
Fermentation of sucrose by Zymomonas mobilis cells attached to stainless steel wire spheres (WS) and to Al2O3 granules was compared with sucrose fermentation by cells entrapped in Ca-alginate. Similar amounts of cell biomass were applied at the beginning of the immobilized fermentation systems. The immobilization of Z. mobilis cells to the carrier surface was checked by scanning electron microscopy (SEM). Most cells were present in holes and pores of Al2O3 surfaces following colonization. Observation of the carrier after repeated fermentation cycles showed that a surface of Al2O3 granules was partly covered by levan. Alginate beads were extended in volume and partly disrupted. Changing the …
Densities, Viscosities, and Refractive Indices of Some Binary Liquid Systems of Methanol + Isomers of Hexanol at 298.15 K
1996
Viscosities, densities, and refractive indices of eight binary liquid systems containing ethanol + some isomers of hexanol have been determined at 298.15 K. The excess property values were fitted to the Redlich-Kister equation to estimate the binary coefficients and the standard deviations.
CO2 conversion in a photocatalytic continuous membrane reactor
2016
The reduction of CO2 with water by using photocatalysts is one of the most promising new methods for achieving CO2 conversion to valuable hydrocarbons such as methanol (MeOH). In this work, prepared TiO2-Nafion (TM)-based membranes were used in a photocatalytic membrane reactor, operated in continuous mode, for converting CO2 to methanol. By using the membrane with the best TiO2 distribution, a MeOH flow rate/TiO2 weight of 45 mu mol (g(catalyst) h)(-1) was measured when operating at 2 bar of feed pressure. This value is higher than those reported in most of the literature data to date. Moreover, methanol production is considered as a relevant advance over the existing literature results wh…