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Selective Extraction (selective + extraction)
Selected AbstractsSelective Extraction of Free Astaxanthin from Haematococcus Culture Using a Tandem Organic Solvent SystemBIOTECHNOLOGY PROGRESS, Issue 4 2007Chang Duk Kang A novel tandem solvent process of dodecane and methanol was developed for the selective extraction of free astaxanthin from red encysted Haematococcus culture. The process consists of dodecane extraction for astaxanthin mixture from the culture (stage 1) and methanol extraction for free astaxanthin from the dodecane extract (stage 2). In the first stage, astaxanthin mixture was directly extracted to dodecane from the culture broth without cell harvest process, followed by a rapid separation of the dodecane extract and the culture medium containing cell debris by simple settling. In the second stage, free astaxanthin was selectively collected to methanol from the dodecane extract, accompanied with saponification of astaxanthin-esters by the addition of NaOH to methanol. During saponification, use of the optimum NaOH concentration (0.02 M) and low temperature (4 °C) reaction minimized the degradation of free astaxanthin, resulting in a total recovery yield of free astaxanthin of over 85%. The free-astaxanthin-containing methanol extract was also simply separated from dodecane by gravity settling, after which the astaxanthin-free dodecane was effectively recycled to the first stage, yielding a stable extractability of astaxanthin mixture during repeated extraction. Our results indicate the potential of the proposed tandem solvent process as an alternative extraction technology for the high-value antioxidant Haematococcus astaxanthin. [source] Selective Extraction of Bioproducts by Ionic LiquidsCHINESE JOURNAL OF CHEMISTRY, Issue 6 2005Wang Jian-Ji Abstract Imidazolium based room temperature ionic liquids have been used to extract selectively L -tryptophan from fermentation broth. anion was found to enhance dramatically the partitioning of L -tryptophan into ionic liquid phase from aqueous solutions. [source] Selective extraction of organic compounds from transesterification reaction mixtures by using ionic liquidsAICHE JOURNAL, Issue 5 2010F. J. Hernández-Fernández Abstract In this article, we describe assays carried out to determine the suitability of 13 ionic liquids based on 1- n -alkyl-3-methylimidazolium and n -alkylpyridinium cations and a wide range of anions (hexafluorophophate, bis{(trifluoromethyl)sulfonyl}imide, tetrafluoroborate, methylsulfate, 2(2-methoxyethoxy)ethylsulfate, ethylsulfate, n -octylsulfate, dicyanamide, nitrate, tetrafluoroborate and chloride) to carry out the selective separation of the organic compounds involved in a transesterification reaction (butyl butyrate, vinyl butyrate, 1-butanol, and butyric acid) from hexane solutions. The assayed ionic liquids were shown to be suitable solvents for the selective separation of the target compounds, the extraction process being controlled by the hydrophobicity of the compounds. The anion composition of the ionic liquid was seen to strongly influence the average extraction ratio, the highest value being reached with the chloride-based ionic liquid. As regards the cation composition of the ionic liquids, it was seen that the average distribution ratio increased with decreasing length of alkyl chain. © 2010 American Institute of Chemical Engineers AIChE J, 2010 [source] Selective extraction of polyunsaturated triacylglycerols using a novel ionic liquid precursor immobilized on a mesoporous complexing adsorbentBIOTECHNOLOGY PROGRESS, Issue 5 2009Patrisha J. Pham Abstract Mesoporous silica (SBA-15) synthesized by using Pluronic123 as the structure-directing template was functionalized by imidazolium-based ionic liquid precursors. Silver salts were then immobilized onto the supported ionic liquids using the incipient wetness impregnation technique. The separation of unsaturated species was achieved through the reversible and specific interaction between silver ions and carbon,carbon double bonds. This adsorbent was examined for the selective separation of polyunsaturated triacylglycerols (PUTAG) using High Pressure Liquid Chromatography (HPLC) with Evaporative Light Scattering Detection (ELSD) as the quantification methodology. AgBF4/SBA15·HPSiOEtIM·PF6 showed an adsorption capacity for linolenin of about 217 mg adsorbed/gram of sorbent. This adsorbent had good selectivity and a high capacity for the most highly unsaturated triacylglycerol when applied to a mixture of triacylglycerols with varying degrees of unsaturation. Consequently, a stepwise methodology was also developed to increase the recovery of the adsorbed components. This adsorbent retained its selectivity and capacity when recycled up to five times. © 2009 American Institute of Chemical Engineers Biotechnol. Prog., 2009 [source] BNP and N-terminal proBNP are both extracted in the normal kidneyEUROPEAN JOURNAL OF CLINICAL INVESTIGATION, Issue 1 2006J. P. Goetze Abstract Background, Increased plasma concentrations of cardiac-derived B-type natriuretic peptide (BNP) and N-terminal pro-B-type natriuretic peptide (proBNP) are both associated with left ventricular dysfunction. Information on the regional elimination of the peptides is, however, still scarce. We therefore examined the renal and peripheral extraction of N-terminal proBNP and BNP. Materials and methods, The study comprised 18 patients with essential arterial hypertension, 51 with cirrhosis, and 18 control patients without kidney or liver disease. All patients underwent a haemodynamic investigation with catheterization of the femoral artery and femoral and renal veins. Blood sampling from the catheters allowed determination of the arteriovenous extraction ratio of N-terminal proBNP and BNP. Results, Neither the peripheral N-terminal proBNP (13, 11, 19 pmol L,1, NS) nor the BNP plasma concentrations (4, 12, 9 pmol L,1, NS) differed between the patient groups. In addition, similar renal extractions were observed in the groups. The renal extraction of N-terminal proBNP (0·16) was not different from that of BNP (0·16). In contrast, the N-terminal proBNP extraction in the lower extremity was markedly lower compared with BNP (0·00 vs. 0·125, P = 0·007). Conclusions, A comparable renal elimination of N-terminal proBNP and BNP is contrasted by a selective extraction of BNP in the lower extremity. Our results suggest a different elimination mechanism in the renal and peripheral circulation, which partly may explain the higher N-terminal proBNP compared with BNP concentrations in normal plasma. [source] Surface podzolization in Cambisols under deciduous forest in the Belgian loess beltEUROPEAN JOURNAL OF SOIL SCIENCE, Issue 1 2000V. Brahy Summary Surface podzolization involves the migration of metal,humus complexes to a depth of a few centimetres. In acid soils derived from loess, this process has been diagnosed mainly by morphological observation. We investigated this process in a toposequence of Luvisols and Cambisols on loess using selective extraction and mineralogical data as well as characteristics of the leaf litter. The humus type (O and OAh horizons) is a moder in the three Luvisols and one of the Cambisols, whereas it is a fibrimor in the two other Cambisols. The contents in total alkaline and alkaline-earth cations range from 35 to 60 cmolc kg,1 in the fibrimor and from 40 to 90 cmolc kg,1 in the moder humus. In the two Cambisols with fibrimor smectite occurs in the clay fraction of the Ah horizon; Fe,humus complexes seem to have moved, but no more than 9 cm, from the Ah to the AB horizon beneath. Relative to the Ah horizon, the upper part of the AB has larger tetraborate-extractable Fe/Al ratio and optical density of the oxalate extract. Such features converge to diagnose surface podzolization in the Cambisols with fibrimor. However, they were not detected in the Cambisol and Luvisols with moder. In the two Cambisols with fibrimor, surface podzolization is consistent with (i) their smaller iron content, (ii) their more advanced weathering stage and (iii) their lower acid neutralizing capacity. [source] Mechanism of lidocaine release from carbomer,lidocaine hydrogelsJOURNAL OF PHARMACEUTICAL SCIENCES, Issue 1 2002Alvaro Jimenez-Kairuz Abstract Rheology, acid-base behavior, and kinetics of lidocaine release of carbomer,lidocaine (CL) hydrogels are reported. A series of (CL)x (x,=,mol% of L,=,25, 50, 75, 100) that covers a pH range between 5.33 and 7.96 was used. Concentrations of ion pair ([R-COO,LH+]) and free species (L) and (LH+) were determined by the selective extraction of (L) with cyclohexane (CH) together with pH measurements, i.e., CH in a ratio CH/hydrogel 2:1 extracted 48% of the whole concentration of lidocaine [LT] of a (CL)100, {[LT],=,([R-COO,LH+]),+,(L),+,(LH+)}. The remaining species in the aqueous phase were distributed as: (L) 3.82%, (LH+) 14.5%, and [R-COO, LH+] 81.7%. Rheology and pH as a function of (CL) concentration are also reported. Delivery rates of free base L were measured in a Franz-type bicompartmental device using water and NaCl 0.9% solution as receptor media. (CL) hydrogels behave as a reservoir that releases the drug at a slow rate. pH effects on rate suggest that, under the main conditions assayed, dissociation of [R-COO,LH+] is the slow step that controls releasing rates. Accordingly, release rate was increased upon addition of a second counterion (i.e., Na+), or through the diffusion of neutral salts such as NaCl, into the matrix of the gel. © 2002 Wiley-Liss, Inc. and the American Pharmaceutical Association J Pharm Sci 91:267,272, 2002 [source] Thermal stability of porous it -PMMA thin film obtained by the extraction of st -PMAA from it -PMMA/st -PMAA stereocomplex with layer-by-layer assembly on a substrateJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 15 2010Hiroharu Ajiro Abstract The functionality of porous isotactic (it) poly(methyl methacrylate) (PMMA) thin films, which were previously developed by the selective extraction of syndiotactic (st) poly(methacrylic acid) (PMAA) from the it -PMMA/st -PMAA stereocomplex thin film on a substrate using the layer-by-layer assembly method was investigated after thermal treatment (70, 80, and 90 °C) in water for 4 h. Quartz crystal microbalance analysis and infrared spectra measurements revealed that the st -PMAA incorporation ability of the porous it -PMMA thin film decreased in order at 80 and 90 °C, while there was no decrease observed at 70 °C. X-ray diffraction analysis also supported the thermal stability of the porosity at 70 °C, whereas two it -PMMA crystalline peaks (2, = 9° and 14°) were generated during heating at 90 °C. The loss of the functionality of the it -PMMA thin film was thus shown to be due to crystallization, which was caused by the increase in polymer-chain mobility during the heating process. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 3265,3270, 2010 [source] Molecularly imprinted polymer for selective extraction of endocrine disrupters nonylphenol and its ethoxylated derivates from environmental solidsJOURNAL OF SEPARATION SCIENCE, JSS, Issue 13 2008Laura Núñez Abstract Nonylphenol isomers (NP), linear nonylphenol (4-n-NP) and NP short chain ethoxylated derivates (NPEO1 and NPEO2) are degradation products of nonylphenol polyethoxylates, a worldwide used group of surfactants. All of them are considered endocrine disrupters due to their ability to mimic natural estrogens. In this paper, the preparation and evaluation of several 4-n-NP molecularly imprinted polymers (MIPs) for the selective extraction and clean-up of 4-n-NP, NP, NPEO1 and NPEO2 from complex environmental solid samples is described. Among the different combinations tested, a methacrylic acid-based imprinted polymer prepared in toluene provided the better performance for molecularly imprinted SPE (MISPE). Under optimum MISPE conditions, the polymer was able to selectively retain not only linear NP but also the endocrine disruptors NPEO1, NPEO2 and NP with recoveries ranging from 60 to 100%, depending upon the analyte. The developed MISPE procedure was successfully used for the determination of 4-n-NP, NP, NPEO1 and NPEO2 in sediments and sludge samples at concentration levels according to data reported in the literature for incurred samples. Finally, various sludge samples collected at five different sewage treatment plants from Madrid and commercial sludge for agriculture purposes were analysed. The measured concentrations of the different compounds varied from 3.7 to 107.5 mg/kg depending upon the analyte and the sample. [source] Selective ultrasound-assisted extractions of lipophilic constituents from Betula alleghaniensis and B. papyrifera wood at low temperaturesPHYTOCHEMICAL ANALYSIS, Issue 4 2007J.-M. Lavoie Abstract Betula alleghaniensis and B. papyrifera are widely distributed in the province of Québec (Canada) and, since these trees are valuable exports for the local lumber industry, large amounts of their residual ligneous biomass are available for further exploitation. Betula species are well known for their significant concentrations of triterpenes, some of which were recently discovered to present promising bioactivity. The secondary transformation of birch biomass could therefore become important for many industries, particularly the pharmaceutical industry. In the present study, extracts from birch sawdust were obtained using an optimised ultrasound-assisted extraction in which the careful choice of temperature permitted a selective extraction of the targeted triterpenes. Moreover, compared with the classical Soxhlet method, higher extraction yields were obtained in a shorter time. The lipophilic extracts obtained using dichloromethane as a solvent were analysed by GC-MS and the major compounds identified as lupane-type cyclic triterpenoids accompanied by the non-cyclic triterpene squalene. Numerous aliphatic long-chain fatty acids were also found in the extracts together with phytosterols. Betulonic acid and squalene, the major extract constituents for both B. alleghaniensis and B. papyrifera, are both bioactive molecules. Copyright © 2007 John Wiley & Sons, Ltd. [source] Selective Extraction of Free Astaxanthin from Haematococcus Culture Using a Tandem Organic Solvent SystemBIOTECHNOLOGY PROGRESS, Issue 4 2007Chang Duk Kang A novel tandem solvent process of dodecane and methanol was developed for the selective extraction of free astaxanthin from red encysted Haematococcus culture. The process consists of dodecane extraction for astaxanthin mixture from the culture (stage 1) and methanol extraction for free astaxanthin from the dodecane extract (stage 2). In the first stage, astaxanthin mixture was directly extracted to dodecane from the culture broth without cell harvest process, followed by a rapid separation of the dodecane extract and the culture medium containing cell debris by simple settling. In the second stage, free astaxanthin was selectively collected to methanol from the dodecane extract, accompanied with saponification of astaxanthin-esters by the addition of NaOH to methanol. During saponification, use of the optimum NaOH concentration (0.02 M) and low temperature (4 °C) reaction minimized the degradation of free astaxanthin, resulting in a total recovery yield of free astaxanthin of over 85%. The free-astaxanthin-containing methanol extract was also simply separated from dodecane by gravity settling, after which the astaxanthin-free dodecane was effectively recycled to the first stage, yielding a stable extractability of astaxanthin mixture during repeated extraction. Our results indicate the potential of the proposed tandem solvent process as an alternative extraction technology for the high-value antioxidant Haematococcus astaxanthin. [source] Removal and Recovery of UO2(??) from Water Samples Using 2,2,-Diamino-4,4,-bithiazole as a New Reagent for Solid Phase ExtractionCHINESE JOURNAL OF CHEMISTRY, Issue 4 2010Majid Soleimani Abstract A novel sensitive and simple method for rapid and selective extraction, preconcentration and determination of uranyl as its 2,2,-diamino-4,4,-bithiazole (DABTZ) complex by using octadecylsilica columns and spectrophotometry is presented. Extraction efficiency and the influence of flow rates of sample solution and eluent, pH, amount of DABTZ, type and least amount of eluent for elution of uranyl complex from columns, break-through volume and limit of detection were evaluated. Also the effects of various cationic and anionic interferences on percent recovery of uranyl were studied. Average extraction efficiency of ca. 90% was obtained by elution of the column with minimal amount of solvent in the presence of interferences. The average preconcentration factor, 136 and a detection limit 0.32 ng·mL,1 were obtained. The method was applied to the recovery and determination of uranyl in different water samples. [source] Global fractionation of oak heartwood extractable polymers (lignins, polysaccharides and ellagitannins) by selective precipitationsJOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 3 2005Marie-Françoise Nonier Abstract This paper introduces a new fractionation method by selective extractions and precipitations making it possible to collect the three groups of oak heartwood extractable polymers in a single operation. The three families, lignins, polysaccharides and ellagitannins, were obtained and each was characterized by different techniques. We grouped together the techniques used to characterize these different oak wood groups of polymers: IR, GC, GC-MS, LC-MS, 1H NMR, SEC, MALDI-TOF/MS. This work focuses on the qualitative aspect only. Copyright © 2004 Society of Chemical Industry [source] | ||||||||||