Separation Of Aqueous Phase Research Articles

Microfluidization of model dairy emulsions. II. Influence of composition and process factors on the protein surface concentration

Summary - The influence of some composition variables (butter oil, sodium caseinate and monoglyceride contents) and process variables (pressure and tempe rature) on the relative adsorbed protein fraction (Fads,%) and on the protein load (I, mg m-2) of fat globules was studied in a model dairy emulsion (oil-in-water produced by microfluidization). The amount of adsorbed proteins (Fadsand F) was evaluated immediately after emulsification by coupling the separation of oil and aqueous phases of the emulsion produced by centrifugation to the determination of protein content. The specifie surface area (Asp) of oil-water interface was obtained by photon correlation spectroscopy after the protein aggregates were dissociated by an appropriate butter. A central composite experimental design was used to obtain Iwo nonlinear multiple regression equations relating Fadsand f to sodium caseinate (0.5 to 3.9 wt%), butter oil (5.2 to 14.7 wt%) and monoglyceride (0.08 to 0.88 wt%) contents, and to the emulsification pressure (7.8 to 76.3 MPa) and temperature (35 to 100 OC). These two functions explained 92.7 and 90.6% of the variation in Fadsand in F, respectively, and made it possible to evaluate the independent influence of each experimental variable. The results indicate that the sodium caseinates (NaCas), as a group, seem much less easily adsorbed th an monoglyceride (glycerol monostearate, GMS) molecules when the GMS:NaCas molecular ratio (R) is higher th an 5: more numerous and possibly more surface active th an proteins, monoglycerides probably settle at the interface quicker th an proteins. A qualitative model is also presented to illustrate this possible competition and estimate its influence on the parameters that characterize protein adsorption (Fadsand F) and fat globule size (dvs).

Polymer-Surfactant Interactions Studied by Phase Behavior, GPC, and NMR

Osmotic effects are important both in static phase behavior and dynamic gel permeation chromatography (GPC) analysis of polymer surfactant systems. Besides affecting the salinity for the II(-)/III phase transition in microemulsions, the water content in the middle phase will decrease when nonassociative, water-soluble polymers are added. The same systems will in a GPC column, using the surfactant solution as eluent, separate both due to osmosis and size exclusion. Association between polyethylene oxide and anionic ethoxylated surfactants disappears if more than three ethylene oxide (EO) groups are added to the surfactant head group. The phase separation of micelles and polymer into separate aqueous phases in the II(-) state occurred at lower salinity when the number of EO groups in the surfactant increased. The phase separation could qualitatively be modeled within a simple Flory-Huggins approach. With NMR self-diffusion measurements it was possible to study if added polymer influenced the structure of the surfactant aggregates.

Water, alkali and char in flash pyrolysis oils

Several biomass flash pyrolysis oils were analyzed to determine the forms of water, alkali and char in the oil. Representative oil samples were produced from oak, pine and switchgrass as representatives of hardwood, softwood and herbaceous biomass, respectively. Separations of the oil were undertaken to confirm the site of the alkali in the oil. Consideration was given to potential for char-encased alkali or alkali precipitation as char; alkali salts in water micro-droplets or alkali soap micelle formations; and organo-alkali component solution in the organic phase. Separations attempted included centrifugation, filtration, water dilutions and phase separations. Microscopic analysis of the oils was also attempted as well as scanning electron microscopic analysis of solids. A separate aqueous phase could not be found in the oil. Size distribution of char particulates showed a range primarily from 1 to 10 μ m. Inorganic components were concentrated in the char particles. Component analysis of the oils affirmed earlier analytical data found in the literature for flash pyrolysis oils.

Radioimmunoassay of Corticosterone using <SUP>125</SUP>I-Labeled Radio-ligand

A radioimmunoassay (RIA) of corticosterone was developed and characterized using 125I labeled radioligand (ICN Biomedicals, U.S.A.) and a single ether extraction procedure. The intra- and interassay coefficients of variation was 7.2% and 14.6% and assay sensitivity was 16.4±3.5 pg per tube. Utilizing this assay, the antiserum for corticosterone (GDN377) made small samples (0.1-1.0μl) use possible. The ease of this technique allows handling of large numbers of samples as compared with RIA using 3H-corticosterone.The specific steps in the procedure of assay were following: 125I-corticosterone was diluted with 0.05M phosphate buffered saline (PBS) containing 1 % bovine serum albumin (BSA). Antiserum (GDN377) was diluted with 0.05M PBS containing 0.05mM ethylenediamine tetraacetic acid, 2Na salt, dihydrate (EDTA) and 0.4% normal rabbit serum (NRS) to 1 : 15000-1 : 20000 dilution. Goat anti-rabbit gamma globulin serum (ARGG) was diluted with 0.05M PBS containing 3.5% polyethylene glycol 6000 (PEG) to 1:150 dilution. Plasma or serum (0.1-1μl) and standard were diluted to 400μl with distilled water in 13 × 100mm culture tubes and extracted once with 2ml of diethyl ether. The samples were allowed to settle for 5 min to ensure separation of ether and aqueous phases. The tubes were then placed in dry ice-ethanol bath to freeze the aqueous phase. The ether phase was then decanted into 12 × 75mm culture tube and dried under reduced pressure with gentle mixing at 50C. One hundred μl of PBS containing 1% BSA, antiserum and labelled ligand (50-100Bq/100μ) were added to each tube and the extract was dissolved by agitation and incubated at 4C for 24 h. Then, 100μl of ARGG was added to each tube. After further incubation for 24 h, the antibody bound hormone was separated from the free hormone by centrifugation at 4C 1700g for 30 min. The supernatant was carefully decanted and the precipitate was counted in automatic gammacounter. Plasma or serum concentrations of corticosterone were calculated using a standard curve.

Effect of temperature on the reversed micellar extraction of enzymes

In “conventional” liquid-liquid extraction of protein solutions with a reversed micellar phase, the protein is transferred from an aqueous phase to the reversed micellar phase by forward extraction, and subsequently to a second aqueous phase during back extraction. This back transfer is a relatively slow process, owing to a large interfacial resistance to mass transfer. In this paper an alternative procedure is described for the back extraction, using the effect of temperature. By increasing the temperature of the reversed micellar phase, after it has been saturated with the aqueous phase during the forward extraction, a separate aqueous phase is formed in which most of the enzyme is concentrated. This excess aqueous phase can be separated easily from the reversed micellar phase by centrifugation. The enzyme can be recovered in this expelled phase at extremely high concentrations (up to 2000 times the initial concentration). This process has been performed continuously using two centrifugal separators, with the reversed micellar phase circulating between the two units. For α-amylase a recovery rate of 73% of the enzyme activity was achieved.

Methods for the determination of partition coefficients based on the effect of solutes upon membrane structure

General procedures are presented for the determination of membrane-water partition coefficients ( K p) based on the measurement of effects that depend on the extent of partitioning. Two cases are deal with: (1) the general case when the effect is an unknown function of the total number of moles of partitioning solute ( n T) and (2) the particular case when the effect is a linear function of n T. The procedure involves the evaluation of the effect as a function of n T for a variety of membrane volumes ( V M), at constant volume of aqueous phase ( V H 2O ), generating a family of curves. It is shown that when a given set of n T, V M produces the same effect, which indicates that the concentration of the solute in the membrane ( n M/ V M) is the same for the whole set, a plot of n T versus V M yields a straight line that allows the calculation of K P. In the particular case when the effect is linearly proportional to n T, the higher V M, the smaller the slope. In this case, these slopes can be used to calculate K P by plotting their inverse as a function of V M. These procedures were applied to the partitioning of a series of compounds, some of them with known K P, in egg phosphatidylcholine (EPC) membranes. The interaction of those compounds with the membrane was monitored either by fluorescence spectroscopy (by measuring either the excimer/monomer ratio or the quenching of intensity of an intercalated probe) or by ESR making use of a lipid spin probe. Compounds with known K P yielded values in good agreement with previously found ones. In principle, the procedures are applicable whenever it is possible to measure a property that depends on the extent of partitioning, allowing the determination of K P from raw data. In particular, it is very adequate for the use of spectroscopic techniques, one main advantage being that no separation of membrane and aqueous phases is required.

Localization of an entrapped item within unilamellar vesicle compartments: use of ultrasound disruption as a procedure to separate aqueous phase and lipidic lamellae.

A procedure has been carried out previously to separate the aqueous phase and the lipidic lamellae from multilamellar liposomes (Bakouche and Gerlier, Analyt. Biochem., 1983, 130, 379). This procedure consisted in multiple short bursts of sonication at a temperature below the transition temperature (Tm) of the lowest melting component followed by an ultracentrifugation. The aqueous phase and the lipidic lamellae were recovered in the supernatant and in the pellet respectively. This procedure was adapted for unilamellar vesicles by modifying the second step of the procedure. A suspension of unilamellar liposomes containing 5,6-carboxyfluorescein (5,6-CF) as a probe for the aqueous phase was disrupted by sonication at low temperature. After gel filtration on to a Sephadex G100 column, the phospholipid bilayers were readily separated from the aqueous probe 5,6-CF. Such a procedure should allow the localization of any item within the unilamellar liposome compartments.

Asymmetric hydrogenation of acetophenone with rhodium(I) complexes of new chiral phosphines derived from amino acids. An unusual modification of the catalyst system

Chiral, N-substituted diphenylphosphinoacetamides were prepared by the acylation of L-aminoacid esters and L-α-phenylethylamine with diphenylphosphinoacetic acid. These compounds were used as ligands in Rh I complex catalysts for hydrogenation of acetophenone and styrene. In the presence of strong, sterically hindered bases the complexes showed low to moderate hydrogenating activity and enantioselectivity. The catalytic activity is enhanced significantly in the presence of a separate aqueous phase.

Behaviour of simple ions in the system cellulose–anionic dye–simple electrolyte. Part 1.—Partition equilibria

The partition equilibria of Na+ and Cl– between a cellulose membrane and an aqueous bath have been studied mainly as a function of the concentration of electrolyte and of ionised acid groups fixed in the membrane. The latter concentration could be varied by the adsorption of suitable amounts of the dye Direct Blue 1. The observed ionic partition behaviour is difficult to reconcile with the standard simple equipotential volume model (EVM) treatment, even allowing for such effects as imperfect experimental separation of membrane and aqueous phases. The EVM with the additional assumption of “cation binding” by the fixed anionic groups can explain the results only empirically. On the other hand, a non-equipotential volume pore model appears to offer a physically more meaningful and acceptable interpretation. However, the single uniformly charged pore model of Schofield et al. requires further elaboration in order to explain the partition behaviour at higher dilution.

A semi-automated fluorometric method for total estrogens in pregnancy urine.

We report a continuous-flow fluorometric method for total urinary estrogens that involves the Kober reaction, with extraction of the reaction product into dichloroethane containing trichloroacetic acid as described by Hahnel and Jones [Clin. Chim. Acta 16, 185 (1967)]. The dichloroethane extraction gives greater stability to the Kober color and sharper separation of aqueous and organic phases. The analytical system is adjusted to give maximum response to estriol 16alpha,beta-D-glucuronide, the principal estrogen conjugate in urine from late pregnancy, when calibrated with estriol standards. An initial 20-fold dilution of the sample with water increased analytical recovery of estriol conjugates from urine while maintaining adequate fluorescent response. Glucose interference was reduced by dilution and eliminated by treatment with sodium borohydride. Urinary protein up to 20 g/liter did not interfere. Total estriol, as determined by gas-liquid chromatography, comprises about 70% of total urinary estrogens in late pregnancy as measured by our continuous-flow fluorometric method. A reference range is presented based on 209 randomly collected urine specimens in which total urinary estrogens are expressed as a ratio to creatinine.

The composition of lipids in intestinal digesta of young pigs receiving diets containing tallow and tallow fatty acids

Three semipurified diets containing a low level of fat or 10 percent of either beef tallow or beef tallow free fatty acids were fed to young pigs. Jejunal digesta was sampled 1.5, 2.5, 3.5, and 4.5 h after feeding by aspiration through tubes leading from the jejunal lumen to the exterior. The samples were forced through Millipore filters (1 x 10(-7) m pore size) to separate aqueous phase and oil phase lipid. The total and aqueous phase lipid was separated into triglyceride, monoglyceride, and free fatty acid, and the fatty acid composition of each fraction determined. The concentration of aqueous phase lipid was not influenced by diet, although the concentration of the oil phase lipid was generally higher for the addition of fat to the diets; the increase was greater for the beef tallow free fatty acid diet than for the beef tallow diet. Free fatty acids were the predominant component of the aqueous phase lipid along with some monoglyceride and traces of triglyceride. The major component of the oil phastions of triglyceride and monoglyceride. These must have been derived from endogenously secreted lipid in the case of the tallow fatty acid diet. Thus, the lower digestibility of completely hydrolyzed beef tallow than of conventional beef tallow was not due to an absence of monoglyceride in the intestinal lumen. The proportion of stearic acid in the jejunal digesta was greater than in the dietary lipid, whereas there were lower proportions of palmitic and oleic acids in the jejunal digesta than in the diet; the effect being most pronounced for the tallow free fatty acid diet. The ratio of oleic to palmitic acid in the aqueous phase was less than in the lipid phase suggesting preferential uptake of oleic acid from the micelle by the intestinal mucosa.

Reactions occurring in the organic phase during aromatic nitrations

AbstractThe reactions which may occur in the organic phase during mononitration of benzene and toluene under heterogeneous conditions used in industry have been studied by mixing the hydrocarbon with a solution of nitrating acid in either m‐mononitrotoluene or mononitrobenzene. Both nitration and oxidation reactions are shown to occur. A separate aqueous phase may be formed during reaction, and distribution of nitric acid into this has an important effect on reaction in the organic phase. The rate of nitration is sensitive to the presence of even traces of sulphuric acid. The ratio of mononitrotoluene isomers formed in the organic phase is the same as under heterogeneous conditions.

Water content of a granite magma deduced from the sequence of crystallization determined experimentally with water-undersaturated conditions

The sequence of crystallization in a biotite-granite from the Bohus batholith of Norway and Sweden, deduced from its texture, was magnetite, plagioclase, microcline, quartz, and finally biotite. Several sequences of crystallization were determined experimentally at 2 kb in the presence of varying only for H_2O contents below 1.2% by weight. The rock was fused to a homogeneous glass, and each experiment included samples of finely crushed rock and glass. The samples were reacted in Ag-Pd capsules with measured H_2O content in coldseal pressure vessels with NNO buffer. With excess H_2O (more than 6.5%) the crystallization interval extends from 865° C to 705° C. In the H_2O-deficient region, the solidus temperature remains unchanged as long as a trace of vapor is present, but the liquidus temperature increases as H_2O content decreases; with 0.8 % H_2O the liquidus temperature is 1125° C, the crystallization interval is 420° C, and a separate aqueous vapor phase is evolved only a few degrees above the solidus at 705° C. The biotite phase boundary increases slightly from 845° C with excess H_2O to 875° C with 1% H_2O, and it intersects the steep phase boundaries for quartz and feldspars; the sequence of crystallization changes at each intersection point. Similar diagrams at various pressures for related rock compositions involving muscovite, biotite and amphibole will provide grids useful in defining limits for the water content of granitic and dioritic magmas. Applications are considered for the Bohus batholith, other granitic rocks, and rhyolites. The Bohus magma could have been formed by crustal anatexis as a mobile assemblage of H_2O-undersaturated liquid and residual crystals with initial total H_2O content less than 1.2%, or it could have been derived by fractionation of a more basic parent with low H_2O content from mantle or subduction zone, but it could not have been derived from a primary andesite generated from mantle peridotite. We consider it unlikely that the H_2O content of large granitic magma bodies exceeds about 1.5% H_2O; these magmas are H_2O-undersaturated through most of their histories. Uprise and progressive crystallization of magma bodies produces H_2O-saturation around margins and in the upper regions of magma chambers. H_2O-saturated rhyolitic and dacitic magmas with phenocrysts can be tapped from the upper parts of the magma chambers.

Liquid ion‐exchange membranes

AbstractA liquid membrane consisting of an oil layer contained between two aqueous phases was found to leak when used to transport ions selectively from one adjacent phase to another. The source of the difficulty was found to be the formation of a separate aqueous phase within the oil layer. This phase could be eliminated by increasing the pressure within the oil layer.The pressure stabilized membrane was then tested and the observed rates of mass and electrical transport compared with values computed using a mathematical model. The comparisons were satisfactory considering the fact that no adjustable parameters were used to fit the data.

Experimental studies of pegmatite genesis; l, A model for the derivation and crystallization of granitic pegmatites

The genesis of granitic igneous pegmatites is here considered in terms of a model conceived from results of field and laboratory studies and subsequently tested by means of experimental investigations. This model emphasizes the roles of water (and/or other relatively volatile substances), both as a dissolved constituent in granitic magmas and as the dominant constituent of a separate fluid phase that is in the supercritical state under most conditions of pegmatite formation. Pegmatite magma, as distinguished by a content of dissolved water that is high relative to the limit of solubility under existing confining pressure, can be formed either through partial melting of crustal materials or as rest-liquid in a cooling igneous body yielding dominantly anhydrous crystalline phases. Such granitic magma can be expected to consolidate according to the following three-fold sequence: 1. Crystallization from hydrous silicate melt, yielding anhydrous solid phases with or without OH-bearing phases. The product is characterized by normal phaneritic textures that generally are coarse grained. It has been termed pegmatite in some occurrences, and granite in others. 2. Crystallization concomitantly from silicate melt and from a coexisting exsolved aqueous fluid of considerably lower viscosity, yielding giant-textured pegmatite along with much finer-grained, even aplitic, mineral aggregates. Segregation of these products can vary enormously in scale and degree. Partitioning of constituents between melt and aqueous fluid, rapid diffusion of constituents through the aqueous phase, and gravitational rising of this fluid through the system contribute to formation of pods, zones, and other rock units of unusual composition and texture. 3. Crystallization in the absence of silicate melt, yielding a wide variety of late-stage products. These include so-called pocket minerals and numerous mineral aggregates formed through exchanges of material among aqueous fluid and earlier-formed crystal-line phases. Development of pegmatite bodies can begin with either Step 1 or Step 2, but it is suggested that the processes involved in Step 2 are essential to the formation of all true pegmatites of igneous origin. The appearance of a second fluid phase, in general a supercritical aqueous fluid derived from the crystallizing melt, is regarded as the decisive event; it is promptly followed by fundamental changes in distribution and texture of the solid phases being formed.The processes can operate effectively in a fully closed system, and they also can modify the surrounding rocks if the system is open at any stage. Step 1 can include reactions between magma and earlier-formed crystals, but far more rapid and extensive exchanges of materials are subsequently effected by processes included in Steps 2 and 3; indeed, such exchanges also can account satisfactorily for pegmatites of metamorphic origin.Crystallization of most granitic magmas in the absence of a separate aqueous phase probably would begin within the temperature range 1,300 degrees -650 degrees C, the specific liquidus temperature depending mainly upon the amounts of volatile constituents held in solution at the time. This compositional factor also would be important in controlling the stage of crystallization\---|late, intermediate, or early\---|at which a separate aqueous fluid would make its appearance. Depending upon confining pressure as dictated by geologic conditions for a given system, the stage in crystallization represented by the presence of both silicate melt and aqueous fluid could begin within about the same temperature range of 1,300 degrees -650 degrees C. Exhaustion of the melt could occur within range extending downward to temperatures of 600 degrees C or even somewhat lower. Textural and structural features appear to be the most reliable indicators of the stages and fundamental processes involved in crystallization of both natural and synthetic pegmatites. The contrasting processes of crystallization from one fluid and from more than one fluid can operate over such broad P-T-X ranges that simple genetic pegmatite classifications based largely upon key minerals, presumed temperature or pressure intervals, or the presence or absence of supercritical conditions appear to be somewhat unrealistic.

Comparative Studies on Plastoquinone II. Analysis for Plastoquinones A, B, C, and D

Two different methods for the extraction and assay of plastoquinones A, B, C and D from chloroplasts of green plants have been described. The long procedure involves separation of aqueous and lipid phases of extract in a separatory funnel, column chromatography, purification on thin-layer plates, and spectrophotometric assays for quantitative determination of the various plastoquinones. The short procedure is based on spotting lipid extracts from chloroplasts on thin layer plates and comparing leucomethylene blue spots of unknown quinones with a series of spots produced by known amounts of the 4 standard plastoquinones on the same plate.Reliability of the 2 procedures is shown by presenting recovery data (82% recovery for PQ A by the long method and 64-100% recovery by the short method). Various solvent systems for quinone purification are described. Separation of plastoquinones B and C into 6 components each is demonstrated for spinach and a tomato mutant, high pigment (hp). Plastoquinone C is shown to be equivalent to C(1)-C(4) while D corresponds to PQ C(5) and C(6) according to Griffiths, Wallwork and Pennock's designation. The term PQ D is therefore redundant and should be abandoned in favor of specific designation of PQ C type.

Mineral Parageneses in Franciscan Metamorphic Rocks, Panoche Pass, California

Approximately 33 square miles of Franciscan terrane near Panoche Pass in the Diablo Range of the central California Coast Ranges were mapped at an initial scale of 1:12,000. Serpentinite intrusions present in the area are not mantled by metasomatic glaucophane schist aureoles, but do appear to contain tectonic inclusions of chloritized eclogite, “glaucophane eclogite,” amphibolite, glaucophane schist, and greenstone. Petrographic and X-ray investigations of country rocks reveal systematic mineral parageneses in metabasalts, metacherts, and metagraywackes. Conversion of greenstones to blueschists involved reaction of albite + actinolite + chlorite to form crossite + lawsonite; greenstones contain calcite, mafic glaucophane schists calcite or aragonite. Least metamorphosed metacherts contain very minor albite + calcite; with progressive recrystallization these phases are replaced by acgirme, riebeckite, and aragonite. Metagraywacke paragenesis is from albite metagraywackes containing accessory lawsonite + calcite or aragonite, to jadeitic pyroxene + law-sonite metagraywackes carrying accessory glaucophane + aragonite. The “jadeitic pyroxene + lawsonite isograd” is recognized on the basis of metagraywacke assemblages. The aragonite isograd cannot be located precisely because of rapid postmetamorphic inversion to calcite. More extreme conditions of recrystallization appear to have been required to produce aragonite and the jadeitic pyroxene + lawsonite (+ quartz) compatibility than to convert greenstones to blueschists. Mineral parageneses and inferred phase relationships in the system CaCO 3 and in the pseudoternary system Ab-An-H 2 O suggest that metamorphism at Panoche Pass involved temperatures of about 200–300°C, lithostatic pressures approaching 7–8 kb, and high chemical potential of H 2 O. Presence of a separate aqueous phase during the metamorphism is indicated. Based on observed mineral assemblages, experimental phase equilibrium data, tectonic and spatial occurrences of blueschists, available geophysical evidence, fossil occurrences, and radiometric dates, the following tentative geologic model is proposed. Franciscan rocks principally of the Diablo Range are hypothesized to have been deposited in an oceanic trench bordering the continental margin in later Jurassic and possibly earliest Cretaceous time. Rapid deposition and subsidence could have accounted for thermal disequilibrium and consequent relatively high pressure, low temperature recrystallization in axial portions of the trench. Thickness of the Franciscan rocks in the Diablo Range is thought to have approached 30 km near the trough axis. Diastrophism nearly contemporaneous with deposition locally deformed the structural trough, resulted in periodic intrusion of serpentinized mantle material and in rapid uplift, and allowed preservation of the blueschist facies mineral assemblages. Elsewhere, portions of the trench apparently were not destroyed and continued to receive sediments well into Cretaceous time.

The comparative biochemistry of developing Ascaris eggs. III. Flavin adenine dinucleotide extracted from unembryonated eggs

Homogenates of unembryonated Ascaris eggs which were extracted with butanol resulted in the separation of a yellow aqueous phase that exhibited only slight turbidity. Such extracts elicited a fluorometric spectrum similar to flavin. The visible absorption spectrum obtained by spectrophotometric assay of concentrated extracts provided further evidence of the flavin nature of the egg preparations. Aqueous extracts of homogenates of unembryonated eggs stimulated d-amino acid oxidase activity, thereby demonstrating the presence of flavin adenine dinucleotide (FAD). Most of the FAD was protein-bound. It was further established electrophoretically that FAD accounted for essentially all of the detectable flavin. No riboflavin or flavin mononucleotide could be detected by the use of electrophoresis.