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Extraction Time (extraction + time)

Distribution by Scientific Domains

Chemistry	84%
Life Sciences	7%
3 Other Domains	9%

Selected Abstracts

Supercritical fluid extraction of walnut kernel oil

EUROPEAN JOURNAL OF LIPID SCIENCE AND TECHNOLOGY, Issue 7 2006
Sema Salg
Abstract The objective of this study was to investigate the effects of the main process parameters on supercritical fluid extraction of walnut (Juglans regia,L.) kernel oil. The recovery of walnut kernel oil was performed in a green and high-tech separation process. CO2 and CO2 +,ethanol mixtures were used as the supercritical solvent. The extraction was carried out at operating pressures of 30, 40 and 50,MPa, operating temperatures of 313, 323 and 333,K, mean particle sizes of 1.78×10,4, 3.03×10,4, 4.78×10,4, 7.00×10,4 and 9.00×10,4,m, supercritical CO2 (SC CO2) flow rates of 1.67×10,8, 3.33×10,8, 6.67×10,8 and 13.33×10,8,m3/s and entrainer (ethanol) concentrations of 2, 4, 8 and 12,vol-%. Maximum extraction yield and oil solubility in SC CO2 obtained at 50,MPa, 333,K, 9.00×10,4,m, 3.33×10,4,m3/h were 0.65,kg oil/kg of dry sample and 37.16,g oil/kg CO2, respectively. The results obtained in this study showed that the crossover pressure effect of walnut kernel oil was at 30,MPa. At 30,MPa and 313,K, the obtained extraction yields above 4,vol-% ethanol reached the organic solvent extraction yield of 68.5,kg oil/kg dry sample. Extraction time was decreased significantly because of the higher solubility of walnut kernel oil in SC CO2 +,ethanol mixtures. [source]

The application of response surface methodology to the production of phenolic extracts of lemon grass, galangal, holy basil and rosemary

INTERNATIONAL JOURNAL OF FOOD SCIENCE & TECHNOLOGY, Issue 2 2006
T. Juntachote
Summary The effects of independent variables (ethanol:water ratio, temperature and time) on the extraction yield and antioxidant properties of phenolic extracts from lemon grass, galangal, holy basil and rosemary were studied. The extraction solvent ratio of ethanol to water was found to have a significant (P < 0.05) influence on extraction yield, reducing power and total phenolic content, but not on the antioxidant activity of all herb and spice samples, while extraction temperature had only minor effects. Extraction time had a significant (P < 0.05) effect only on the reducing power of holy basil extracts. The optimum extraction conditions, i.e. extraction solvent ratio of ethanol to water, extraction temperature and extraction time for maximum total phenolic content, were 3:1 at 25 °C for 30 min for lemon grass, 3:1 at 75 °C for 90 min for galangal and holy basil and 3:1 at 75 °C for 30 min for rosemary. [source]

Optimisation of the headspace-solid phase microextraction for organomercury and organotin compound determination in sediment and biota

JOURNAL OF SEPARATION SCIENCE, JSS, Issue 4 2008
Alejandra Delgado
Abstract Headspace solid-phase microextraction was optimised for the simultaneous preconcentration of methylmercury (MeHg+), monobutyltin, dibutyltin, tributyltin, monophenyltin (MPhT), diphenyltin (DPhT), and triphenyltin (TPhT) from sediments and biota. Extraction time (3,24 min), extraction temperature (20,90°C), desorption time (1,10.4 min), desorption temperature (152,260°C), and sample volume (5,22 mL) were simultaneously optimised, while variables such as fibre type (30 ,m polydimethylsiloxane, PDMS), pH (acetic acid/sodium acetate, HOAc/NaOAc, 2 mol/L, pH , 4.8), the concentration of the derivatisation agent (sodium tetraethylborate, NaBEt4, 0.1% m/v), and the ionic strength (fixed by the buffer solution) were kept constant. The variables were optimised according to the experiments proposed by the MultiSimplex program and the responses were considered in order to establish the optimum conditions. The repeatability (relative standard deviation, RSD, 5,20.6%) and limits of detection (LODs, 0.05,0.97 ng/g) of the overall method were also estimated. The lowest precisions were obtained for DPhT and TPhT. The optimised preconcentration method was applied to the determination of MeHg+, butyl- and phenyltins in certified reference materials (IAEA-405 MeHg+ in estuarine sediment, BCR-646 butyl- and phenyltins in marine sediment, BCR-463 MeHg+ in tuna fish, DOLT-2 MeHg+ in dogfish liver, and BCR-477 butyltins in mussel tissue) by GC with microwave-induced plasma/atomic-emission detection. [source]

New supported liquid membrane-capillary electrophoresis in-line arrangement for direct selective analysis of complex samples

ELECTROPHORESIS, Issue 15 2006
Leonor Nozal
Abstract An in-line coupling of a micro-membrane extraction unit, based on supported liquid membrane, with commercially available capillary electrophoresis equipment is described. A main characteristic of this micro-membrane device, made from a simple Eppendorf tube, is that it permits the application of voltage in the acceptor solution to be applied during the extraction process. This has been shown as an alternative to enhance sensitivity, as the analytical signal achieved by applying 10,kV for 20,min was similar to that obtained without the application of voltage and with extraction time of 60,min. In addition, the design has been made permitting both in-line hydrodynamic and electrokinetic sample introduction into the electrophoretic capillary. The analytical potential of the proposed system has been demonstrated by the direct determination of nitroimidazoles from pig liver tissue. The high efficiency of the proposed system allowed the extraction and the determination of the analytes to be performed from a simple tissue homogenate obtained in water. The precision of the analysis of spiked samples, expressed in terms of relative standard deviation, was better than 4.8%. [source]

Determination of thiol compounds by automated headspace solid-phase microextraction with in-fiber derivatization

FLAVOUR AND FRAGRANCE JOURNAL, Issue 3 2006
Qing Wang
Abstract In this article, headspace solid-phase microextraction (HS-SPME) analysis of thiol compounds with both solid and aqueous samples was investigated using N -phenylmaleimide as an in-fiber derivatization reagent. The derivatives were analyzed using GC-MS. The HS-SPME method was executed on an automatic sampler and optimized by studying a variety of factors such as the selection of the fiber, extraction time, temperature, agitation speed, etc. Method validation was carried out by spiking known amounts of thiol compounds into the sample and calculating the concentration by standard addition. The relative standard deviations (RSD) for the majority of the thiols were less than 10%. The developed method resulted in a limit of detection (LOD) in the low microgram per liter for most of the thiols analyzed, which was about one order of magnitude lower than the HS-SPME without derivatization. Finally, the overall method was successfully applied for the determination of thiols in yellow onion, green onion and garlic. Copyright © 2006 John Wiley & Sons, Ltd. [source]

Recovery of water-soluble constituents of rose oil using simultaneous distillation,extraction

FLAVOUR AND FRAGRANCE JOURNAL, Issue 6 2005
Mohammad H. Eikani
Abstract Recovery of water-soluble constituents of rose oil from aqueous solutions using simultaneous distillation,extraction was studied. Experiments were carried out using a modified Likens,Nickerson apparatus. A preliminary study was first performed on aqueous 2-phenylethanol solutions. Using n -butyl acetate as the solvent, the effects of extraction time, solvent volume and solute concentration on recovery yields were investigated. The optimum experimental conditions obtained from the preliminary study were applied to extract rose oil constituents from actual aqueous solutions, such as rose water, second distillation water and residual water of Iranian rose (Rosa damascena Mill). The results show that a representative extract with recovery of the most valuable constituents of rose oil was carried out successfully. Copyright © 2005 John Wiley & Sons, Ltd. [source]

A heat-stable trypsin inhibitor in adzuki bean (Vigna angularis): effect of extraction media, purification and biochemical characteristics

INTERNATIONAL JOURNAL OF FOOD SCIENCE & TECHNOLOGY, Issue 1 2010
Sappasith Klomklao
Summary Trypsin inhibitor from adzuki bean (Vigna angularis) seed was isolated and characterised. Extraction of seed with NaCl at the concentration of 0.15 m showed a higher recovery of trypsin inhibitor than other solvents tested (P < 0.05). Optimal extraction time for the recovery trypsin inhibitor from adzuki bean seed was 30 min (P < 0.05). Purification of inhibitor was achieved by heat-treatment at 90 °C for 10 min, followed by ammonium sulphate precipitation with 30,65% saturation and size exclusion chromatography on Sephacryl S-200, presenting a yield and purification of 53.9% and 10.91-fold, respectively. The apparent molecular weight of trypsin inhibitor was estimated to be 14 kDa based on SDS-PAGE and inhibitor activity of zones separated by electrophoresis. The purified inhibitor was stable over a broad pH range and retained high inhibitory activity toward trypsin after incubation at 90 °C for 60 min. NaCl, at 0,3% concentration, did not affect the inhibitory activity of purified trypsin inhibitor, however, the activity was lost when sample was treated with ,-mercaptoethanol prior to electrophoresis. [source]

The optimization of microwave-assisted extraction of decursin from Angelica gigas Nakai root

INTERNATIONAL JOURNAL OF FOOD SCIENCE & TECHNOLOGY, Issue 7 2006
Gee-Dong Lee
Summary Response surface methodology was used to display the characteristics of microwave-assisted extraction (MAE) of soluble solids and decursin from Angelica gigas Nakai root, thereby allowing MAE conditions to be optimized. These included ethanol concentration, microwave power and extraction time. The maximal solid yield was predicted to be 44.2% under conditions of 44.9% ethanol concentration, 115.6 W microwave power and 5.8 min extraction time. Decursin content of the extract was estimated to be maximal at 2.52% using 97.7% ethanol, 90.2 W microwave power, and 6.1 min extraction time. The estimated optimal MAE conditions (67% ethanol, 100 W and 6 min) to maximize both components were verified by comparing estimated values with experimental values (42.2% soluble solids, 2.2% decursin), which were higher than those (35.8% solids, 2.0% decursin) obtained by conventional reflux extraction (60% ethanol, 95 °C and 6 h). [source]

The application of response surface methodology to the production of phenolic extracts of lemon grass, galangal, holy basil and rosemary

Removal of heavy metals from municipal solid waste incineration (MSWI) fly ash by traditional and microwave acid extraction

JOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 9 2010
Jun Xue
Abstract BACKGROUND: Municipal solid waste incinerator (MSWI) fly ash is regarded as hazardous waste because it contains various toxic metals. A previous study has shown that fly ash can be detoxified by removal of heavy metals. In this work, the extractability of heavy metals from MSWI fly ash by traditional and microwave acid extraction were compared. RESULTS: A 24 , 1 fractional factorial experimental design was adopted using acid concentration, extraction time, temperature, and liquid/solid (L/S) ratio as the experimental factors for traditional extraction, and acid concentration, extraction time, liquid/solid (L/S) ratio and microwave power as the experimental factors for microwave extraction. The traditional extraction results show that L/S played an important role in Zn, Cd extraction while L/S ratio and extractant concentration were important for Pb extraction. However, no controlling parameter was determined for Cu and Cr extraction. For the microwave extraction, it was shown that L/S was important for Pb and Zn and extractant concentration was important for Pb, Zn and Cd. The time and the power were not significant for the extractability of heavy metals. CONCLUSION: Hydrochloric acid was an effective extractant. Microwave heating promoted extraction and shortened extraction time. Microwave acid extraction treatment is a potentially feasible method for the removal of heavy metals from MSWI fly ash. Copyright © 2010 Society of Chemical Industry [source]

APPLICATION OF ULTRASONICATION OR HIGH-PRESSURE EXTRACTION OF FLAVONOIDS FROM LITCHI FRUIT PERICARP

JOURNAL OF FOOD PROCESS ENGINEERING, Issue 6 2009
K. NAGENDRA PRASAD
ABSTRACT Litchi (Litchi chinensis Sonn.) fruit pericarp (LFP) contains a high amount of flavonoids, which could be used as natural antioxidants. Some emerging novel technologies, such as ultrasonic extraction (UE) and high-pressure extraction (HPE), have exhibited great potential for flavonoid extraction. Experiments were conducted to comparatively investigate the effects of conventional extraction (CE), 40-KHz UE and 200- or 400-MPa HPE on the extraction efficiency of flavonoids from LFP. After 30 min of extraction, the extract yield, total phenolic content, 1,1-diphenyl-2-picrylhydrazyl radical scavenging activity and superoxide anion scavenging ability were examined. The crude extract yields by the UE, 400 HPE and CE were 24, 30 and 1.83%, respectively. However, there were no significant differences (P > 0.05) in the total phenolic content and antioxidant activity tested among these three different extractions at the same concentration. In addition, two flavonoids, namely epicatechin and epicatechin gallate, were identified and quantified as the major compounds, while catechin and procyanidin B2 were identified as the minor compounds. The total flavonoid content detected was 0.65, 0.75, 0.29 and 0.07 mg/g dry weight by HPE at 200 and 400 MPs, UE, and CE, respectively. Thus, the HPE technique showed a higher efficiency in extracting flavonoids from LFP, and the HPE could reduce the extraction time and increase the amount of the extracted phenolics. PRACTICAL APPLICATIONS Litchi (Litchi chinensis Sonn.) is a subtropical fruit that originated in Southeast Asia. As litchi fruit is gradually accepted by consumers for its delicious taste and attractive red skin, litchi production has steadily increased in recent decades, with increasing exports to Europe and North America from both the southern and northern hemisphere production areas. Litchi fruit pericarp (LFP) accounts for approximately 16% by weight of the whole fresh fruit and is comprised of a significant amount of flavonoids. Therefore, LFP tissues may be considered an important source of dietary flavonoids. This work showed that HPE technique has a high efficiency in extracting flavonoids from LFP tissues, which may help the litchi industry develop new extraction methods to better utilize the flavonoids from LFP tissues. [source]

RECOVERY OF SINAPIC ACID FROM A WASTE STREAM IN THE PROCESSING OF YELLOW MUSTARD PROTEIN ISOLATE

JOURNAL OF FOOD PROCESS ENGINEERING, Issue 2 2008
N. PRAPAKORNWIRIYA
ABSTRACT A large amount of waste permeates generated from the processing of yellow mustard protein was concentrated fivefold using a nanofilter with a molecular weight cut off of 1,000 Da, while approximately 74% of sinapic acid was retained. Sinapic acid was then released from sinapine, its esterified form, by an alkaline hydrolysis. The hydrolyzed solution was acidified to prevent oxidation of the sinapic acid and to precipitate the remaining proteins. Subsequently, sinapic acid and other phenolics were extracted by a two-stage extraction using a mixture of diethyl ether and ethyl acetate (1:1), 165-min extraction time and permeate-to-solvent ratio of 1:2. Approximately 95% of the sinapic acid in the acidified permeate was finally concentrated in the solvent phase. PRACTICAL APPLICATIONS This development has led to an economical process to recover phenolics and to treat effluent from a process of oilseed protein while reducing the use of water during the extraction of protein. A reduction of water usage makes the processing of oilseed protein isolate more economically attractive, and the recovered phenolics may find a use as a nutraceutical. The developed process is not only limited to the recovery of phenolics from mustard, but also applied for recovering phenolic acids, specifically sinapic acid, from waste water from membrane processing of protein from mustard and similar polyphenol-containing oilseeds. [source]

Extraction and Removal of Caffeine from Green Tea by Ultrasonic-Enhanced Supercritical Fluid

JOURNAL OF FOOD SCIENCE, Issue 4 2010
Wei-Qiang Tang
ABSTRACT:, Low-caffeine or caffeine-removed tea and its products are widely welcomed on market in recent years. In the present study, we adopt ultrasonic-enhanced supercritical fluid extraction process to remove caffeine from green tea. An orthogonal experiment (L16 (45)) was applied to optimize the best removal conditions. Extraction pressure, extraction time, power of ultrasound, moisture content, and temperature were the main factors to influence the removal rate of caffeine from green tea. The 5 factors chosen for the present investigation were based on the results of a single-factor test. The optimum removal conditions were determined as follows: extraction pressure of 30 MPa, temperature at 55 °C, time of 4 h, 30% moisture content, and ultrasound power of 100 W. Chromatogram and ultraviolet analysis of raw material and decaffeinates suggests that under optimized conditions, the caffeine of green tea was effectively removed and minished without damaging the structure of active ingredients in green tea. [source]

Tuna Pepsin: Characteristics and Its Use for Collagen Extraction from the Skin of Threadfin Bream (Nemipterus spp.)

JOURNAL OF FOOD SCIENCE, Issue 5 2008
S. Nalinanon
ABSTRACT:, Pepsin from the stomach of albacore tuna, skipjack tuna, and tongol tuna was characterized. Pepsin from all tuna species showed maximal activity at pH 2.0 and 50 °C when hemoglobin was used as a substrate. Among the stomach extract of all species tested, that of albacore tuna showed the highest activity (40.55 units/g tissue) (P < 0.05). Substrate-Native-PAGE revealed that pepsin from albacore tuna and tongol tuna consisted of 2 isoforms, whereas pepsin from skipjack tuna had only 1 form. The activity was completely inhibited by pepstatin A, while EDTA (ethylenediaminetetraacetic acid), SBTI (soybean trypsin inhibitor), and E-64 (1-(L -trans-epoxysuccinyl-leucylamino)-4-guanidinobutane) exhibited negligible effect. The activity was strongly inhibited by SDS (sodium dodecyl sulfate) (0.05% to 0.1%, w/v). Cysteine (5 to 50 mM) also showed an inhibitory effect in a concentration dependent manner. ATP, molybdate, NaCl, MgCl2, and CaCl2 had no impact on the activity. When tuna pepsin (10 units/g defatted skin) was used for collagen extraction from the skin of threadfin bream for 12 h, the yield of collagen increased by 1.84- to 2.32-fold and albacore pepsin showed the comparable extraction efficacy to porcine pepsin. The yield generally increased with increasing extraction time (P < 0.05). All collagen obtained with the aid of tuna pepsin showed similar protein patterns compared with those found in acid-solubilized collagen. Nevertheless, pepsin from skipjack tuna caused the degradation of , and , components. All collagens were classified as type I with large portion of ,-chain. However, proteins with molecular weight (MW) greater than 200 kDa were abundant in acid-solubilized collagen. [source]

DECREASE IN DYNAMIC VISCOSITY AND AVERAGE MOLECULAR WEIGHT OF ALGINATE FROM LAMINARIA DIGITATA DURING ALKALINE EXTRACTION,

JOURNAL OF PHYCOLOGY, Issue 2 2008
Peggy Vauchel
Alginates are natural polysaccharides that are extracted from brown seaweeds and widely used for their rheological properties. The central step in the extraction protocol used in the alginate industry is the alkaline extraction, which requires several hours. In this study, a significant decrease in alginate dynamic viscosity was observed after 2 h of alkaline treatment. Intrinsic viscosity and average molecular weight of alginates from alkaline extractions 1,4 h in duration were determined, indicating depolymerization of alginates: average molecular weight decreased significantly during the extraction, falling by a factor of 5 between 1 and 4 h of extraction. These results suggested that reducing extraction time could enable preserving the rheological properties of the extracted alginates. [source]

Identification and determination of the saikosaponins in Radix bupleuri by accelerated solvent extraction combined with rapid-resolution LC-MS

JOURNAL OF SEPARATION SCIENCE, JSS, Issue 13 2010
Yun-Yun Yang
Abstract A method based on accelerated solvent extraction combined with rapid-resolution LC,MS for efficient extraction, rapid separation, online identification and accurate determination of the saikosaponins (SSs) in Radix bupleuri (RB) was developed. The RB samples were extracted by accelerated solvent extraction using 70% aqueous ethanol v/v as solvent, at a temperature of 120°C and pressure of 100,bar, with 10,min of static extraction time and three extraction cycles. Rapid-resolution LC separation was performed by using a C18 column at gradient elution of water (containing 0.5% formic acid) and acetonitrile, and the major constituents were well separated within 20,min. A TOF-MS and an IT-MS were used for online identification of the major constituents, and 27 SSs were identified or tentatively identified. Five major bioactive SSs (SSa, SSc, SSd, 6,- O -acetyl-SSa and 6,- O -acetyl-SSd) with obvious peak areas and good resolution were chosen as benchmark substances, and a triple quadrupole MS operating in multiple-reaction monitoring mode was used for their quantitative analysis. A total of 16 RB samples from different regions of China were analyzed. The results indicated that the method was rapid, efficient, accurate and suitable for use in the quality control of RB. [source]

Enantioselective analysis of mirtazapine, demethylmirtazapine and 8-hydroxy mirtazapine in human urine after solid-phase microextraction

JOURNAL OF SEPARATION SCIENCE, JSS, Issue 2 2010
Fernando José Malagueño de Santana
Abstract A selective and reproducible off-line solid-phase microextraction procedure was developed for the simultaneous enantioselective determination of mirtazapine (MRT), demethylmirtazapine and 8-hydroxymirtazapine in human urine. CE was used for optimization of the extraction procedure whereas LC-MS was used for method validation and application. The influence of important factors in the solid-phase microextraction efficiency is discussed, such as the fiber coatings, extraction time, pH, ionic strength, temperature and desorption time. Before extraction, human urine samples were submitted to enzymatic hydrolysis at 37°C for 16,h. Then, the enzyme was precipitated with trichloroacetic acid and the pH was adjusted to 8 with 1,mol/L pH 11 phosphate buffer solution. In the extraction, the analytes were transferred from the aqueous solution to the polydimethylsiloxane-divinylbenzene fiber coating and then desorbed in methanol. The mean recoveries were 5.4, 1.7 and 1.0% for MRT, demethylmirtazapine and 8-hydroxymirtazapine enantiomers, respectively. The method was linear over the concentration range of 62,1250,ng/mL. The within-day and between-day assay precision and accuracy were lower than 15%. The method was successfully employed in a preliminary cumulative urinary excretion study after administration of racemic MRT to a healthy volunteer. [source]

Headspace solid-phase microextraction for direct determination of volatile phenols in cider

JOURNAL OF SEPARATION SCIENCE, JSS, Issue 21 2009
Consuelo Pizarro
Abstract A headspace solid-phase microextraction coupled to gas chromatography-tandem mass spectrometry (GC-MS/MS) method was optimised and validated for the determination of 4-ethylguaiacol, 4-ethylphenol, 4-vinylguaiacol and 4-vinylphenol, involved in the presence of Brett character, in ciders. The influence of different parameters on extraction efficiency (fibre coating, salt addition, exposure time, extraction temperature and sample volume/total volume ratio) was evaluated. Divinylbenzene/carboxen/PDMS was selected as extraction fibre and the other optimised parameters were as follows: 10,mL of cider, temperature 70°C, extraction time 60,min and addition of 0.4,g/mL of NaCl. The proposed method showed satisfactory linearity. The detection limits obtained were 0.01,,g/L for 4-ethylguaiacol, 0.02,,g/L for 4-ethylphenol, 0.08,,g/L for 4-vinylguaiacol and 0.03,,g/L for 4-vinylphenol. These detection limits were lower than those obtained in previous studies on the determination of volatile phenols in other alcoholic beverages. Good recoveries of over 95% were observed for all compounds, and the repeatability obtained was considered acceptable, ranging between 4 and 10%. To demonstrate the feasibility of the procedure, the method was applied to the analysis of commercial ciders. To our knowledge, this is the first time that the headspace solid-phase microextraction procedure has been optimised to determine specifically the Brett character responsible compounds in cider. [source]

Potential of combining of liquid membranes and molecularly imprinted polymers in extraction of 17,-estradiol from aqueous samples

JOURNAL OF SEPARATION SCIENCE, JSS, Issue 11 2009
Olga Nemulenzi
Abstract The potential of combination of liquid membranes (microporous membrane liquid,liquid extraction) and molecularly imprinted polymers (MIPs) was performed using 17,-estradiol (E2) as model compound. The model compound was extracted from aqueous sample through a hydrophobic porous membrane that was impregnated with hexane/ethyl acetate (3:2), which also formed part of the acceptor phase. In the acceptor phase, the compound was bound onto MIP particles that were also part of the organic phase. The potential of such combination was optimised for the type and amount of MIP particles in the organic acceptor phase, the extraction time, and the type of organic acceptor solvent. Ultrasound assisted binding of E2 onto MIP particles was also investigated. MIPs prepared by precipitation polymerization were found to be superior to those prepared by bulk polymerization. Increase in the extraction time and the amount of MIP particles in the acceptor phase led to more E2 binding onto the MIP particles. Hexane/ethyl acetate (3:2) as an organic acceptor was found to give higher E2 binding onto MIP particles compared to toluene, diethyl ether, and hexane. Ultrasound was furthermore found to increase the binding of E2 onto MIP particles. The selectivity of the technique was demonstrated by extracting wastewater and where clean chromatograms were obtained compared to liquid membrane extractions (SLMs) alone. [source]

An efficient combination of supercritical fluid extraction and high-speed counter-current chromatography to extract and purify homoisoflavonoids from Ophiopogon japonicus (Thunb.) Ker-Gawler

JOURNAL OF SEPARATION SCIENCE, JSS, Issue 11 2009
Chengjun Ma
Abstract Supercritical fluid extraction (SFE) was used to extract homoisoflavonoids from Ophiopogon japonicus (Thunb.) Ker-Gawler. The optimization of parameters was carried out using an orthogonal test L9 (3)4 including pressure, temperature, dynamic extraction time and the amount of modifier. The process was then scaled up by 100 times with a preparative SFE system under the optimized conditions of 25 MPa, 55°C, 4.0 h and 25% methanol as a modifier. Then crude extracts were separated and purified by high-speed counter-current chromatography (HSCCC) with a two-phase solvent system composed of n -hexane/ethyl acetate/methanol/ACN/water (1.8:1.0:1.0:1.2:1.0 v/v). There three homoisoflavonoidal compounds including methylophiopogonanone A 6-aldehydo-isoophiopogonone A, and 6-formyl-isoophiopogonanone A, were successfully isolated and purified in one step. The collected fractions were analyzed by HPLC. In each operation, 140 mg crude extracts was separated and yielded 15.3 mg of methylophiopogonanone A (96.9% purity), 4.1 mg of 6-aldehydo-isoophiopogonone A (98.3% purity) and 13.5 mg of 6-formyl-isoophiopogonanone A (97.3% purity) respectively. The chemical structure of the three homoisoflavonoids are identified by means of ESI-MS and NMR analysis. [source]

Application of continual injection liquid-phase microextraction method coupled with liquid chromatography to the analysis of organophosphorus pesticides

JOURNAL OF SEPARATION SCIENCE, JSS, Issue 4 2009
Yanuardi Raharjo
Abstract A liquid-phase microextraction coupled with LC method has been developed for the determination of organophosphorus pesticides (methidation, quinalphos and profenofos) in drinking water samples. In this method, a small amount (3 ,L) of isooctane as the acceptor phase was introduced continually to fill-up the channel of a 1.5 cm polypropylene hollow fiber using a microsyringe while the hollow fiber was immersed in an aqueous donor solution. A portion of the acceptor phase (ca. 0.4 ,L) was first introduced into the hollow fiber and additional amounts (ca. 0.2 ,L) of the acceptor phase were introduced to replenish at intervals of 3 min until set end of extraction (40 min). After extraction, the acceptor phase was withdrawn and transferred into a 2 mL vial for a drying step prior to injection into a LC system. Parameters that affect the extraction efficiency were studied including the organic solvent, length of fiber, volume of acceptor and donor phase, stirring rate, extraction time, and effect of salting out. The proposed method provided good enrichment factors of up to 189.50, with RSD ranging from 0.10 to 0.29%, analyte recoveries of over 79.80% and good linearity ranging from 10.0 to 1.25 mg/L. The LOD ranged from 2.86 to 82.66 ,g/L. This method was applied successfully to the determination of organophosphorus pesticides in selected drinking water samples. [source]

Analysis of 51 persistent organic pollutants in soil by means of ultrasonic solvent extraction and stir bar sorptive extraction GC-MS

JOURNAL OF SEPARATION SCIENCE, JSS, Issue 20 2008
Marta Martínez-Parreño
Abstract A novel method based on ultrasonic solvent extraction and stir bar sorptive extraction (SBSE) for the analysis of 51 persistent organic pollutants including organochlorine pesticides (OCPs), polychlorinated biphenyls (PCBs), polycyclic aromatic hydrocarbons (PAHs), and polybrominated diphenylethers (PBDEs) in soil samples was developed. The different parameters that affect both the extraction of analytes from the soil samples, such as solvent selection, solvent volume, mass of soil, and extraction time, and the partitioning from the solvent/water mixture to the PDMS were studied. The final selected conditions consisted of the extraction of 1 g of soil with 15 mL methanol by sonication for 30 min. The methanol extract was mixed with 85 mL of Milli-Q water and extracted by means of SBSE for 14 h at 900 rpm. The stir bars were analyzed by thermal desorption-GC-mass spectometry (TD-GC-MS). The effects of the matrix on the recovery of the various pollutants under the developed method were studied using two soils with very different physicochemical properties. Method sensitivity, linearity, repeatability, and reproducibility were also studied. Validation and accuracy of the method were conducted by analyzing two commercial certified reference materials (CRMs). The main advantage of this method resides in the fact that a small amount of a nontoxic solvent (methanol) is needed for the extraction of only 1 g of solid sample allowing LODs ranging from 0.01 to 2.0 ,g/kg. Repeatability and reproducibility variations were lower than 20% for all investigated compounds. Results of the CRMs verify the high accuracy of this method. [source]

Supercritical fluid extraction of ecdysterone from the roots of Achyranthes bidentata BL.

JOURNAL OF SEPARATION SCIENCE, JSS, Issue 8 2008
Yizhe Zheng
Abstract Ecdysterone has been found in a great many plants and animals and has some valuable pharmaceutical properties. The present study was conducted to investigate optimal conditions for the extraction of the compound by supercritical fluid extraction from the roots of Achyranthes bidentata BL. An orthogonal array design (OAD), OA9(34), was employed as a chemometric method for optimization of the extraction of ecdysterone from the herbal medicine. Four parameters, namely, pressure and temperature of the supercritical fluid, the dynamic extraction time, and the flow rate of dimethyl sulfoxide, were studied and optimized by a three-level OAD. Determinations of the extracts were performed by high-performance liquid chromatography. The effects of the parameters were studied using analysis of variance. The results shown that the yield of ecdysterone could be influenced by the four parameters to a similar degree. The yield for DMSO-modified supercritical CO2 was in the range from 0.65 to 1.03 mg/g under the selected conditions. In comparison with methanol-modified supercritical CO2 and Soxhlet extraction, a higher yield was obtained when DMSO-modified supercritical CO2 was used. [source]

Determination of gastrodin and vanillyl alcohol in Gastrodia elata Blume by pressurized liquid extraction at room temperature

JOURNAL OF SEPARATION SCIENCE, JSS, Issue 13 2007
Eng Shi Ong
Abstract Pressurized liquid extraction (PLE) at room temperature with a laboratory-assembled system was applied for the extraction of gastrodin (GA) and vanillyl alcohol (VA) in Gastrodia elata Blume. The proposed system setup for this current work was simpler as no heating and backpressure regulator was required. Extraction with PLE was carried out dynamically at a flow rate of 1.5 mL/min, at room temperature, under an applied pressure of 10,20 bars with an extraction time of 40,50 min. The extraction efficiencies of the proposed method using 20% aqueous ethanol were compared with heating under reflux using organic solvents such as methanol and ethanol/water (20:80) for different batches of medicinal plant materials. For the determination of GA and VA in G. elata Blume, the extraction efficiencies of PLE at room temperature were observed to be comparable with heating under reflux. The method precision was found to vary from 1.6 to 8.6% (RSD, n = 6) on different days. The marker compounds present in the various medicinal plant extracts were determined by gradient elution HPLC and HPLC/MS/MS. Our work demonstrated the possibility of implementation of PLE at room temperature and the advantages of minimizing the use of organic solvents in the extraction process. [source]

Chemical composition of mate tea leaves (Ilex paraguariensis): A study of extraction methods

JOURNAL OF SEPARATION SCIENCE, JSS, Issue 18 2006
Rosângela Assis Jacques
Abstract The objective of this work was to investigate the extraction of Ilex paraguariensis leaves by means of three extraction techniques: pressurized liquid extraction (PLE, also called accelerated solvent extraction , ASE), maceration, and sonication. Samples of mate tea leaves were collected from an experiment conducted under agronomic control at Indústria e Comércio de Erva-Mate Bar,o LTDA, Brazil. Six solvents with increasing polarities (n -hexane, toluene, dichloromethane, ethyl acetate, acetone, and methanol) were used in this investigation. Chemical analysis of the extracts was performed by GC coupled with a mass spectrometer detector. The identification and quantification were accomplished by coinjections of certified standards. The results showed that no significant differences in the qualities of the extracts were noticed regarding the extraction methods. On the other hand, the PLE technique was found to be more effective for the extractions of caffeine, phytol, palmitic, and stearic acid. The use of PLE led to a significant decrease in the total extraction time, amount of solvent consumption, and manipulation of samples compared to maceration and ultrasound-assisted extraction methods. [source]

Application of water as a solvent in microwave-assisted extraction for analysis of PCBs and CBzs in fly ash

JOURNAL OF SEPARATION SCIENCE, JSS, Issue 6 2005
Yifei Sun
Abstract Polychlorinated biphenyls (PCBs) and chlorobenzenes (CBzs) are two classes of dioxin precursors formed in municipal solid waste incinerators (MSWIs); they produce negative health effects similar to those of dioxins. Reducing the analytical time required for determining the concentrations of these compounds in MSWIs is important for quickly evaluating their importance and assessing associated health risks. In the present study, water is used as a safe and environmentally friendly solvent in microwave-assisted extraction (MAE) for PCB and CBz analyses. MAE is compared with traditional Soxhlet extraction (SE) to determine the extraction efficiencies. The evaluation of extraction efficiencies shows that MAE has a high extraction efficiency compared with that of SE when water content is lower than 60%. Furthermore, the extraction time and organic solvent consumption are reduced with MAE compared with SE. [source]

Effects of processing and storage on walnut (Juglans regia L) tannins,

JOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 13 2001
Kar Wai Clara Sze-Tao
Abstract Walnut tannins were maximally extracted with absolute methanol and an extraction time of 60,min. Storage (21 days at 25,°C) significantly reduced (20,40% reduction) the assayable tannin content in walnuts. The ranges of tannin content in freshly cracked inshell and shelled walnuts were respectively 372,1095 and 363,667,mg catechin equivalent per 100,g dry weight. The assayable tannin content in inshell and shelled walnuts was 10,20% higher when the particle size was reduced from 2- to 8-mesh. Using 0.5 as compared to 2% (w/v) vanillin as colour development reagent yielded 15,20% higher assayable tannin contents. The assay colour development reached a maximum after 20,min of incubation at 25,°C. Roasting (204,°C for 5,min) caused a small (14%) but significant reduction in assayable tannins. Soaking in aqueous alkali solutions was more effective (44,100% reduction) than soaking in aqueous acid solutions (6,76% reduction) in decreasing the assayable tannin content in walnuts. Microwave heating in distilled deionised water resulted in 93,98% reduction in walnut assayable tannins. Blanching at 100,°C for 2,min was as effective as alkali soaking in significantly reducing the amount of extractable walnut tannins (98% reduction). The tannin content in blanched walnuts was positively related to astringency scores (r,,=,0.92). © 2001 Society of Chemical Industry [source]

Safety and quality of plastic food contact materials.

PACKAGING TECHNOLOGY AND SCIENCE, Issue 5 2003
Optimization of extraction time, based on arithmetic rules derived from mathematical description of diffusion., extraction yield
Abstract Migration of packaging constituents into food may raise concerns about food safety. This paper describes the conclusions of a EU research project (AIR 941025), aiming to facilitate the introduction of migration control into good manufacturing practice and into enforcement policies. The first part describes a re-evaluation of analytical approaches to extract and identify potential migrants released by plastic materials, viz. comparison of analytical methods, choice of extraction solvents and of fat simulants. Here we focus on the extraction time needed to achieve a given extraction yield. By correlating these parameters with simple and practical equations, it is possible to design alternative tests for control of compliance of packaging plastics. Using a reference experiment (where there is good agreement between experimental and calculated kinetic curves), it is possible to calculate the percentage of extraction which can be achieved in a given time, or the time necessary to reach a target extraction level for other polymer/solvent combinations. A global control scheme is proposed, which indicates whether and when calculation and testing should be applied. Guidelines are proposed, and can be adapted to both industrial control and to enforcement laboratories. Copyright © 2003 John Wiley & Sons, Ltd. [source]

Microwave-assisted extraction of total bioactive saponin fraction from Gymnema sylvestre with reference to gymnemagenin: a potential biomarker

PHYTOCHEMICAL ANALYSIS, Issue 6 2009
Vivekananda Mandal
Abstract Objective , To develop a fast and ecofriendly microwave assisted extraction (MAE) technique for the effective and exhaustive extraction of gymnemagenin as an indicative biomarker for the quality control of Gymnema sylvestre. Methodology , Several extraction parameters such as microwave power, extraction time, solvent composition, pre-leaching time, loading ratio and extraction cycle were studied for the determination of the optimum extraction condition. Scanning electron micrographs were obtained to elucidate the mechanism of extraction Results , The final optimum extraction conditions as obtained from the study were: 40% microwave power, 6,min irradiation time, 85% v/v methanol as the extraction solvent, 15,min pre-leaching time and 25,:,1 (mL/g) as the solvent-to-material loading ratio. The proposed extraction technique produced a maximum yield of 4.3% w/w gymnemagenin in 6,min which was 1.3, 2.5 and 1.95 times more efficient than 6,h of heat reflux, 24,h of maceration and stirring extraction, respectively. A synergistic heat and mass transfer theory was also proposed to support the extraction mechanism Conclusion , Comparison with conventional extraction methods revealed that MAE could save considerable amounts of time and energy, whilst the reduction of volume of organic solvent consumed provides an ecofriendly feature. Copyright © 2009 John Wiley & Sons, Ltd. [source]

Microwave-assisted extraction of the main phenolic compounds in flaxseed

PHYTOCHEMICAL ANALYSIS, Issue 4 2007
Vickram Beejmohun
Abstract A microwave-assisted extraction (MAE) method has been applied for the first time to the extraction of the main lignan, secoisolariciresinol diglucoside (SDG), and the two most concentrated hydroxycinnamic acid glucosides in flaxseed. The effects of microwave power, extraction time and alkaline treatment were investigated. It was shown that a 3 min MAE resulted in an SDG content of 16.1 ± 0.4 mg/g, a p -coumaric acid glucoside content of 3.7 ± 0.2 mg/g and a ferulic acid glucoside content of 4.1 ± 0.2 mg/g. These values were compared with those obtained using conventional extraction methods and the results demonstrated that MAE was more effective in terms of both yield and time consumption. Copyright © 2007 John Wiley & Sons, Ltd. [source]