Solvent Extraction

Evaluation of emerging diesel-particulate emissions control technology will require analytical procedures capable of continuous measurement of transient organic and elemental carbon emissions. Procedures based on the flame ionization properties of organic carbon and ...

The purpose of the study was to optimise analytical methods for determination of the chemical speciation of mercury in studies of protective mechanisms of selenium. Optimisation of the methods was performed using CRM DOLT-2 (Dogfish liver), both in its original form and after separation of various fractions. The sample was homogenised with 10 mM Tris-HCl buffer (pH 7.6) and ultracentrifuged. The soluble phase obtained was applied to a size exclusion chromatography column (Sephadex G-75 column) for separation of various protein fractions. Total mercury (total Hg), monomethyl mercury (MeHg) and selenium (Se) were determined in whole dogfish liver tissue and its soluble and insoluble phases (pellet). Different approaches for determination of total Hg and MeHg were compared. Simultaneous determination of MeHg and inorganic mercury (Hg2+) was based on alkaline dissolution and/or acid leaching, followed by ethylation, room temperature precollection, isothermal gas chromatography (GC), pyr...

The scarcity of sizeable specimens of normal oral mucosa for experimental purposes has hampered research on oral epithelium. Because large specimens of viable human vaginal mucosa are readily available and because vaginal and buccal epithelia are microscopically similar, vaginal mucosa has been used successfully to establish a human cyst model in experimental animals. The ultrastructure and distribution of keratin filaments in these epithelia are also similar, as is their permeability to water and a number of chemical substances. Therefore, if vaginal mucosa could be substituted for buccal mucosa it would expedite research on the epithelium of buccal mucosa. To strengthen further the concept that vaginal epithelium could replace buccal epithelium in certain experimental studies, the thickness of these epithelia, their patterns of surface keratinization, the presence or absence of intercellular lipid lamellae and their lipid contents were now compared. Thirty-three specimens of vaginal mucosa from postmenopausal women and 36 of buccal mucosa were investigated. To compare the thickness of the epithelial layers the number of cell layers in sections of 20 vaginal and 20 buccal mucosal specimens were counted in the three thickest and three thinnest regions of each specimen. Surface keratinization was evaluated on sections stained with the Picro-Mallory method. To demonstrate lipid lamellae two vaginal and two buccal mucosa specimens were examined electron microscopically after normal fixation and postfixation in ruthenium tetroxide. Following solvent extraction of 11 vaginal and 14 buccal epithelia, quantitative lipid analyses were performed using thin-layer chromatography. No statistically significant differences were found between the maximum and minimum number of epithelial cell layers. The patterns of surface keratinization and the distribution and appearance of the lipid lamellae in the intercellular spaces were similar. The lipid composition of the two epithelia corresponded, except for the cholesterol esters and glycosylceramides, which were higher in buccal epithelium. Ceramides for vaginal epithelium and triglycerides for buccal epithelium were not determined. Based on structural similarities, a similar lipid composition and earlier findings, it is concluded that vaginal epithelium can be used as a substitute for buccal epithelium in certain in vitro, and possibly for in vivo, studies.

1 Facultad de Ingeniería. Universidad Autónoma de Chihuahua Apartado Postal 1528 “C”. Ciudad Universitaria, Chihuahua, Chih., México 31160 2 Centro de Investigación de Materiales Avanzados (CIMAV), Av. Miguel de Cervantes Saavedra 120. Chihuahua, Chih., México 31109 3 ...

The selection of separation process of organic compounds is a critical issue in the chemical industry. Different conventional methods, such as coagulation, precipitation, ion exchange, electrodialysis, adsorption, ultrafiltration and liquid-liquid extraction have been used for the separation processes since last so many years, but supported liquid membrane (SLM)-based separation processes have been predicted as a promising option. Ionic liquids (ILs) are considered a new miraculous chemical due their unique properties and large variety of applications in all areas of the chemical sciences. The use of ionic liquids as a liquid membrane phase results in the stabilization of the SLMs due to their negligible vapor pressure, possibility of minimizing their solubility in the surrounding phases and greater capillary force associated with their high viscosity, which can reduce the displacement of liquids from micron pores under pressure. This review article summarizes the role of ionic liquids in supported liquid membrane technology for extraction processes, stability of the membranes and show promise in the liquid/liquid extraction of organics from water, gases, amino acids, toxic metal ions from their aqueous solution and separating isomeric organic compounds. © 2011 Elsevier B.V.

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Copper(II) chelates of the Schiff bases (H2L), obtained by condensation of 4-butyryl-3-methyl-1-phenyl-pyrazoline-5-one (HBMPP) with o-phenylene diamine (H2L1) and p-phenylene diamine (H2L2), have been prepared and characterized by elemental analyses, thermogravimetric analyses, magnetic measurements, diffuse reflectance spectra, IR and mass spectra, and conductance measurements. The extractability of copper(II) with H2L in chloroform was examined. Effective extraction was observed with 1 × 10−3 mol dm−3 of ligands at pH 6.5 using H2L1 and pH 7.0 using H2L2. The nature of the extracted species was ascertained by the slope analysis method. The ligand can effectively be used in solvent extraction of copper(II) from aqueous phase to organic phase.

The present study focuses on the influence of the composting process on the formation of potentially bioavailable and sequestrated PAH fractions. The potentially bioavailable fraction was determined by means of a mild-solvent extraction (with n-butanol). The total and potentially bioavailable PAH content was evaluated in the consecutive composting stages, i.e. at the onset of the experiment, after the stabilization phase (on the 35th day), and after the maturation phase (on the 76th day). Four municipal sewage sludges with differentiated PAH content were selected for the present experiment. Eleven PAHs from the US EPA list (with exception of naphthalene, acenaphthylene, acenaphtene, fluorene and benz[ah]anthracene) were determined for the purpose of this experiment. The content of the total PAHs ranged from 3052 to 10 352 μg kg−1. The share of the potentially bioavailable fraction was at a similar level in the sludge samples tested and ranged from 75% to 81%. Greater differences were noted in the share of the bioavailable fraction in the case of individual PAH groups. The influence of the composting process on the contribution of the potentially bioavailable fraction of the PAH clearly depended on the stage of the experiment and sewage sludge type. However, in the case of all sludges, a lowering of the bioavailable fraction by 19–52% as compared to the level at the outset of the experiment was observed. During the first phase (stabilization) of the sewage sludge composting process, a reduction of the PAH content took place mainly at the expense of potentially bioavailable fraction, whereas in the second phase (maturation), sequestration processes predominated. The above phenomenon was most clearly visible for the 6-rings PAHs.

Designing pores of nanoscale dimension into a magnetic material can engineer the surface nanostructure, resulting in a mesoporous material with unique physicochemical properties. Here we report a simple soft-templating approach for the synthesis of new mesoporous iron oxide materials having semi-crystalline pore wall by using an anionic surfactant sodiumdodecylsulfate as the structure-directing agent (SDA) or template at low temperature. On removal of the SDA molecules through solvent extraction the mesostructure is preserved and the material shows considerably high BET surface area and type IV isotherms corresponding to the mesopores. This mesoporous Fe2O3 material showed superparamagnetic behavior and hence this template-assisted synthesis of mesoporous Fe2O3 can find its potential utility in designing magnetic nanostructured materials.

The purpose of the study was to optimise analytical methods for determination of the chemical speciation of mercury in studies of protective mechanisms of selenium. Optimisation of the methods was performed using CRM DOLT-2 (Dogfish liver), both in its original form and after separation of various fractions. The sample was homogenised with 10 mM Tris-HCl buffer (pH 7.6) and ultracentrifuged. The soluble phase obtained was applied to a size exclusion chromatography column (Sephadex G-75 column) for separation of various protein fractions. Total mercury (total Hg), monomethyl mercury (MeHg) and selenium (Se) were determined in whole dogfish liver tissue and its soluble and insoluble phases (pellet). Different approaches for determination of total Hg and MeHg were compared. Simultaneous determination of MeHg and inorganic mercury (Hg2+) was based on alkaline dissolution and/or acid leaching, followed by ethylation, room temperature precollection, isothermal gas chromatography (GC), pyr...

Mulberry (Morus) belongs to the Moraceae plant family, native of China. The leaves of mulberry plant are the major food source for the silkworm. The leaf consists of minerals, vitamins, dietary fibre, amino acids, phytosterols, flavonoids and other functional components, mainly 1-DNJ (1-Deoxynojirimycin) which acts as an anti-diabetic drug. In countries like China, Korea and Japan the preparations from mulberry leaves are used as medicine for increasing the immunity of the human body, cough relief and to lower the blood sugar and blood pressure. The high nutritional value of leaves is used as a functional food, mostly in the form of herbal tea, smoothie, yoghurt, salads, nutritional masala biscuits, capsules, dry powder, oil, dietary supplement etc. This manuscript mainly focuses on the nutritional importance and health benefits of mulberry leaves extract. The leaves extract may help to lower blood sugar (diabetes), inflammation levels, cholesterol and fighting against heart disease.

Bioerodible polymers used in controlled drug delivery systems, such as poly(lactic-co-glycolic acid) (PLGA) undergo radiolytic degradation during γ-irradiation. In spite of the considerable practical importance, yet only little knowledge is available on the consequences of this sterilization method on the resulting drug release patterns in a quantitative way. The major objectives of the present study were: (i) to monitor the

This study aimed to characterize waste cooking oil as a potential green solvent for liquid-liquid extraction (LLE). Three samples of waste cooking oil ranging from yellow to brown in colour were studied. The physicochemical properties of oil investigated include density, viscosity, free fatty acid (FFA) content, acid value and functional groups. The density and viscosity of oil were measured by a pycnometer and a viscometer, respectively, whereas the FFA content and acid values were determined by acid-base titration. It was found that there was no significant difference in density for all samples of oil studied, but the viscosity (46.5 – 56.5 cP), FFA content (0.60 – 6.42%) and acid value (1.19 – 12.78%) increased with the darkness of oil colour. FTIR evaluation of functional groups revealed that all types of oil studied had similar functional groups. Since the physicochemical properties of waste cooking oil were found to be compatible with those of fresh cooking oil, waste cooking oil is a potential low-cost replacement for fresh cooking oil that has been used successfully as a solvent in LLE processes.