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PubMed2005

Novel reactive perstraction system applied to the hydrolysis of penicillin G.

The activity of penicillin acylase has been studied in aqueous and organic solvents, as free enzyme as well as immobilized within the membrane of liquid-core capsules. The activity of the enzyme is inhibited by the accumulation of the products of the hydrolysis reaction, namely phenyl acetic acid (PAA). In order to overcome this inhibition a range of organic solvents were tested for use in in situ product recovery. Of these solvents dibutyl sebacate (DBS) was chosen due to the rapid extraction rate, the high logP and to facilitate capsule production. The extraction efficiency at pH 3.5 for PAA was >80% for phase ratios of >50% free solvent with partition coefficients of 8 and 0.7 for PAA and penicillin G (PenG), respectively, thereby showing that PAA could be selectively extracted at pH 3.5 and 25 degrees C. Liquid-core capsules containing DBS were shown to efficiently remove PAA selectively and the PAA could be effectively back-extracted and the capsules re-used in a three-stage process resulting in high product separation. Immobilization of penicillin acylase onto the capsule membranes resulted in increased operational stability of the enzyme and a very high enzyme activity. Over 53.3% of the PAA formed could be recovered in the capsule core with a concentration over sevenfold higher than in the aqueous phase. Higher extraction efficiencies could be obtained by varying the substrate concentration and number of capsules. The enzyme immobilized on capsules could be stored for over 4 months at pH 8 and 4 degrees C with no loss of activity. Over 80% of the initial activity could be recovered over five repeated batch cycles of the bioconversion process. The importance of capsular perstraction and reactive capsular perstraction has been clearly demonstrated.

Dicarboxylic Acids↗
PubMed1987

Measurement of tulobuterol in human plasma by capillary gas chromatography and selected ion monitoring detection.

A method is described for the quantification of tulobuterol in human plasma, based upon selective extraction and high resolution capillary gas chromatography-mass spectrometry. The mass spectrometric determination is based on selected ion monitoring of two fragment ions derived from the N,O-heptafluorobutyryl derivatives of tulobuterol and its internal standard, deschlorotulobuterol. The plasma work-up procedure consists of extraction of 1.0 ml alkalinised plasma with dichloromethane, back-extraction into an acidified aqueous phase, followed by a final extraction with dichloromethane after realkalinisation. The method gave interference-free and linear results. The between-assay variability is 4.7% CV at the 3.0 micrograms l-1 plasma concentration level. The assay permitted quantitative measurements down to 170 ng tulobuterol per litre of plasma and hence provided sufficient sensitivity for quantification of plasma levels after therapeutic doses.

Bronchodilator Agents↗
PubMed2006

A rapid fractionation method for heavy metals in soil by continuous-flow sequential extraction assisted by focused microwaves.

A microwave-assisted continuous-flow sequential extraction system was developed for rapid fractionation analysis of heavy metals in soil. Insertion of pressure-adjusted air between the extractants provided stable flows of the extractants without mutual mixing and back-pressure influence of a column packed with soil, thereby facilitating reliable continuous-flow extractions. In addition, use of pure water as a pumping solvent removed metal contamination because of direct contact between corrosive extractants and the pump containing metallic materials. Focused microwave irradiation to the soil accelerated the selective extractions of the acid-soluble and reducible fractions of heavy metals in soil in the first and second steps of the sequential extraction conditions, as defined by the Commission of the European Bureau of Reference (BCR). The microwave-assisted continuous-flow extraction provided high correlations in amounts of six heavy metals except Zn in the first step and Cu in the second step extracted from a reference sludge soil, BCR CRM 483, with a conventional batchwise extraction proposed by BCR; continuous-flow extraction assisted by conductive heating provided lower correlations for all the six metals. The proposed method drastically reduced the time required for the sequence extraction to ca. 65 min without losing accuracy and precision of the fractionation analysis of heavy metals in soil, whereas the BCR batchwise method requires ca. 33 h.

Chemical Fractionation↗
PubMed2003

Before the injection--modern methods of sample preparation for separation techniques.

The importance of sample preparation methods as the first stage in an analytical procedure is emphasised and examined. Examples are given of the extraction and concentration of analytes from solid, liquid and gas phase matrices, including solvent phase extractions, such as supercritical fluids and superheated water extraction, solid-phase extraction and solid-phase microextraction, headspace analysis and vapour trapping. The potential role of selective extraction methods, including molecular imprinted phases and affinity columns, are considered. For problem samples alternative approaches, such as derivatisation are discussed, and potential new approaches minimising sample preparation are noted.

Chromatography↗
PubMed2005

Isotopic constraints on the fate of petroleum residues sequestered in salt marsh sediments.

To provide a new perspective on the fate of petroleum in the marine environment, we utilized variations in the natural abundance of radiocarbon (14C) to detect and quantify petroleum residues that have persisted in Wild Harbor sediments, West Falmouth, MA, for more than 30 years. The 5730-yr half-life of 14C makes this isotope ideal for the detection of fossil-fuel-derived contaminants (14C free) within different fractions of natural organic matter (modern 14C content) in environmental matrixes. Samples of both contaminated and uncontaminated sediments were sequentially treated, first by solvent extraction, followed by saponification, and then acid hydrolysis. Radiocarbon analysis of the sediment residues and select extracts was performed to probe for the presence of fossil fuel contaminants and/or their metabolites in different pools of sedimentary organic matter. Our results indicate that the majority of fossil carbon is solvent-extractable and has not been incorporated in the insoluble organic matter in sediment. Unextracted sediments contaminated with petroleum contain significantly less 14C than extracted sediments, and isotope mass balance calculations suggest that up to approximately 9% of the total organic carbon (TOC) in the petroleum contaminated sediment horizons is derived from solvent-extractable petroleum. These estimates are similar to values calculated when the total quantities of oil (measured by gas chromatography with flame ionization detector (GC-FID)) are compared to TOC content (determined by elemental analysis). These results pave the way for applications of this isotopic approach to more complex environmental systems where the fate of contaminants is less certain.

Accidents↗
PubMed2007

Anion partitioning and ion-pairing behavior of anions in the extraction of cesium salts by 4,5' '-Bis(tert-octylbenzo)dibenzo-24-crown-8 in 1,2-dichloroethane.

A systematic study of anion partitioning and ion pairing was performed for an extraction of individual cesium salts into 1,2-dichloroethane (1,2-DCE) using 4,5' '-bis(tert-octylbenzo)dibenzo-24-crown-8 as the cesium receptor. Equilibrium constants corresponding to the extraction of ion pairs and dissociated ions, formation of the 1:1 cesium/crown complex (confirmed by electrospray mass spectrometry), and dissociation of the ion pairs in water-saturated 1,2-DCE at 25 degrees C were obtained from equilibrium modeling using the SXLSQI program. The standard Gibbs energy of partitioning between water and water-saturated 1,2-DCE was determined for picrate, permanganate, trifluoromethanesulfonate, methanesulfonate, trifluoroacetate, and acetate anions. The dissociation of the organic-phase complex ion pair [Cs(4,4' '-bis(tert-octylbenzo)dibenzo-24-crown-8]+NO3- observed in the extraction experiments was shown to be consistent with the dissociation constant determined independently by conductance measurements. As attributed to the large effective radius of the complex cation, the evident anion discrimination due to ion pairing in the 1,2-DCE phase was relatively small, by comparison only a tenth of the discrimination exhibited by the anion partitioning. Only chloride and picrate exhibit evidence for significantly greater-than-expected ion-pairing tendency. These results provide insight into the inclusion properties of the clefts formed by opposing arene rings of the crown ether upon encapsulation of the Cs+ ion, whose weak anion recognition likely reflects the preferential inclusion of 1,2-DCE molecules in the clefts. Observed anion extraction selectivity in this system, which may be ascribed predominantly to solvent-induced Hofmeister bias selectivity toward large charge-diffuse anions, was nearly the same whether cesium salts were extracted as dissociated ions or ion pairs.

Journal Article↗
PubMed2002

Extraction of cereal prolamins and their toxicity in coeliac disease.

Simple extraction of prolamins from cereal flour using 70% aqueous ethanol leads to co-extraction of lipids and other secondary products. Treatment of the crude extract with an excess of pure ethanol resulted in the removal of the majority of these compounds. Prolamin extracts obtained following ethanol precipitation showed little difference to products of more complex, multi stage, selective extractions, when compared using MALDI-TOF mass spectrometry. Toxicity tests on enzymic digests of ethanol-precipitated prolamins from coeliac-toxic cereals, coeliac-non-toxic cereals and oats were carried out using a rat liver lysosome assay. The prolamins from the ethanol-precipitated extracts showed greater activity than those extracted using only 70% ethanol for extraction. As the ethanol precipitation method is simple and provides a prolamin extract of sufficient purity for further evaluation, this procedure has been adopted as an alternative to more tedious procedures for preparation of cereal prolamins.

Animals↗
PubMed2001

Extractibility of the protein and peptide fraction for different types of dry fermented sausages in relation to GPC-analysis.

The use of GPC (gel filtration chromatography) for investigating the proteolysis during fermentation and ripening of dry fermented sausages (Northern and Mediterranean type) and the choice of a suitable extraction solvent for this technique was evaluated. Solvents in a wide range of acidity were used in this experiment (pH 0.5-13). A calculation of the percentage extracted nitrogencompounds for each solvent and a comparison of the GPC-profile for each extract select the HCl-dilutions with a pH 1 to 3 as the most suitable extraction solvent. Although very basic solvents extract most of the protein and peptide fraction, they lead to some degradation of the proteins and peptides and are not reliable. Clear differences between the GPC-profiles for both types of sausages were not observed.

Animals↗
PubMed1998

Dose-dependent selective cytotoxicity of extracts from marine green alga, Cladophoropsis vaucheriaeformis, against mouse leukemia L1210 cells.

The selective cytotoxic activity of extracts from two marine green algae, Cladophoropsis vaucheriaeformis and Halimeda discoidea, was examined via a dose response assay against mouse leukemia L1210 cells and normal NIH-3T3 cells. The MeOH-extract from C. vaucheriaeformis showed selective cytotoxicity to L1210 cells at concentrations ranging from 50 to 100 microg/ml. In particular, the greatest selectivity for cytotoxic activity was found at the concentration of 50 microg/ml, at which the growth of L1210 cells was inhibited completely and that of NIH-3T3 was not affected at all. However, MeOH extracts from the red alga Laurencia okamurae and the brown alga Dictyopteris undulata, which displayed non-selective cytotoxicity in our previous screening program, did not show similar selective cytotoxicity at any concentrations tested. These results indicate that the marine green alga C. vaucheriaeformis may contain a unique antitumor substance with selective cytotoxic activity against L1210 cells. Our results also suggest that this active substance might be of low molecular weight and therefore MeOH-soluble.

Animals↗
PubMed1983

The inefficacy of polivalent Pasteurella multocida vaccines for sheep.

Immunity assays on sheep sera using passive mouse protection tests showed that vaccines containing more than 4 strains of Pasteurella multocida did not give a good immunity. The immune response was not enhanced by the use of an oil adjuvant, and high concentrations of bacteria had only a partial positive effect. Attempts to extract selectively the protection-inducing antigen(s) from P. multocida by veronal, phenol or potassium thiocyanate extraction were unsuccessful. Furthermore, it was found that sheep antisera to the recognized type strains of P. multocida afforded only limited protection against a number of field strains. We concluded from this that successful immunization against ovine pasteurellosis will depend on either the identification of a strain of P. multocida that gives a wide spectrum of immunity or the discovery of a live mutant suitable for vaccine production and the definition of cultural conditions that promote the expression of a common immunizing antigen.

Animals↗
PubMed1982

Feedback regulation of granulopoiesis: polymerization of lactoferrin abrogates its ability to inhibit CSA production.

Neutrophil extracts were prepared from the peripheral blood of 40 normal volunteers and tested for their ability to inhibit CSA production by mononuclear leukocytes. Highly dilute neutrophil extracts inhibited CSA production/release, while extracts selectively depleted of lactoferrin by antibody affinity chromatography did not. In addition, higher concentrations of neutrophil extracts and higher doses of lactoferrin (10(-9)-10(-6) M) failed to inhibit CSA production/release. We found no evidence of CSA or CSA-enhancing factors in either our lactoferrin or our neutrophil extracts. However, using gel chromatography and rate zonal density sedimentation, we noted that lactoferrin undergoes concentration-dependent polymerization at 10(-9)-10(-10) M in tissue culture medium and that while monomeric lactoferrin effectively inhibits CSA production/release in vitro, the polymeric form does not. Thus, while we have confirmed that lactoferrin is the activity in neutrophil extracts that inhibits CSA production, we have also found that lactoferrin undergoes reversible polymerization at physiologic concentrations and that the polymerized molecule is inactive. The tendency of lactoferrin to polymerize in tissue culture medium and in vivo should be taken into account in any studies on its potential role as a physiologically relevant regulator of granulopoiesis.

Centrifugation, Density Gradient↗
PubMedDate not supplied

Hydroxyamidines as new extracting reagents for spectrophotometric determination of cadmium with 4-(2-pyridylazo)naphthol in industrial effluents, coal, and fly ash.

A simple, sensitive, and selective extractive spectrophotometric method for the determination of cadmium in trace quantities with N1-hydroxy-N1,N2-diphenylbenzamidine (HDPBA) and 4-(2-pyridylazo)naphthol (PAN) is described. The method is based on the extraction of cadmium with HDPBA into chloroform at pH 9.0 +/- 0.2 and simultaneous spectrophotometric determination with PAN. The binary Cd(II)-HDPBA complex extracted into chloroform has a molar absorptivity of 1.96 x 10(4) L/mol/cm at lambda max 400 nm. The sensitivity of the yellow Cd(II)-HDPBA complex was increased remarkably by the addition of PAN to the binary complex. With 6 different hydroxyamidines tested, the red-orange complex in chloroform exhibited maximum absorbance at 530-550 nm, with molar absorptivity values of 3.2-5.6 x 10(4) L/mol/cm. The method adheres to Beer's law up to 1.5 micrograms cadmium/mL organic phase. The detection limit of the method is 0.02 micrograms Cd/mL. Investigations of the effect of foreign ions revealed that the present method is free from matrix interference of most of the common ions (e.g., Fe(III), Ni(II), Cu(II), Mn(II), V(V), Co(II), Al(III), Cu(II), Mg(II), and Mo(VI)). The relative standard deviation for 10 repetitive analyses of the metal was 1.4%. The validity of the method was tested successfully with various environmental samples.

Amidines↗
PubMed2006

Ion imprinted polymer particles for separation of yttrium from selected lanthanides.

Lanthanide(III) (Dy, Gd, Tb and Y) ion imprinted polymer (IIP) materials were synthesized via single pot reaction by mixing lanthanide imprint ion with 5,7-dichloroquinoline-8-ol, 4-vinylpyridine, styrene, divinylbenzene and 2,2'-azobisisobutyronitrile in 2-methoxyethanol porogen. The imprint ion was removed by stirring the above materials (after powdering) with 6 mol/L HCl to obtain the respective lanthanide IIP particles. Y-Dy, Y-Gd and Dy-Gd polymer particles were obtained by physically mixing equal amounts of the respective leached individual lanthanide(III) particles. Control polymer (CP) particles were similarly prepared without imprint ion. Application of the above synthesized polymer particles was tested for separation of Y from Dy, Gd and Tb employing batch and column SPE methods using inductively coupled plasma atomic emission spectrometry for the determination. Optimization studies show that Y present in 500 mL can be preconcentrated using Dy-Gd IIP particles and eluted with 20 mL of 1.0 mol/L of HCl, providing an enrichment factor of approximately 25. Dy-Gd IIP particles offer higher selectivity coefficients for Y over other lanthanides compared to other IIP particles and commercial liquid-liquid extractants. Selectivity studies for Y over other coexisting inorganic species (other than lanthanides) were also conducted and the results obtained show a quantitative separation of Y from other inorganics other than Cu(II) and Fe(III). Furthermore, both batch and column studies indicate the purification of yttrium concentrate from 55.0 +/- 0.2 to 65.2 +/- 0.2% in a single stage of operation.

Journal Article↗
PubMed1985

Immunocytochemical studies using a monoclonal antibody to bovine cardiac titin on intact and extracted myofibrils.

A monoclonal antibody specific to bovine cardiac titin has been identified. The antibody recognizes a common antigenic site in striated muscles of several species. In relaxed myofibrils, specific staining at the A-I junction resulted in a doublet of fluorescent bands within a sarcomere. The distance between the doublets in successive sarcomeres varied according to the degree of myofibrillar contraction. Staining on formamide-extracted myofibrils has confirmed that this epitope is located near the outer edges of isolated A bands. Selective extraction of myofibrillar proteins resulted in different staining patterns. Disrupting the structural integrity of the M-line or the A-band centre caused a significant amount of titin to translocate toward the Z-line region. In contrast, shortening of the A-band by removal of myosin from the ends of the thick filaments resulted in anti-titin staining moving closer to the M-line region. Several conclusions can be drawn from this study: (a) two aligned groups of titin molecules are placed symmetrically to the M-line in a sarcomere; (b) titin may attach directly or via intermediary protein(s) to sites near the M-line and Z-line such that the protein is under tension and (c) removal of proteins from either region results in titin staining in the opposite region. However, the edges of the A-band give some hindrance to collapse of the titin toward the M-line.

Animals↗
PubMed2006

Optimization and evaluation of a procedure for the gas chromatographic-mass spectrometric analysis of the aromas generated by fast acid hydrolysis of flavor precursors extracted from grapes.

A procedure has been developed for the GC-MS analysis of the aromas released in fast acid hydrolysis of precursor fractions from grape musts and skins. Different sorbents for the extraction of the precursors were compared. The best results were obtained with LiChrolut EN polymeric resins which displayed two and six-fold more extraction capacity than Amberlite XAD-2 resins and C18 sorbents, respectively. C18 sorbents are more suitable for selective extraction of less polar precursors. The initial version of the method was imprecise and so the imprecision of the different steps was assessed. The maceration of the solid parts and the liquid-liquid extraction of the aromas released in the acid hydrolysis proved to be the critical steps. Greater crushing of the solid parts and solid-phase extraction (SPE) instead of liquid-liquid extraction (LLE) improved reproducibility. In the method finally proposed about 100 aromatic components belonging to four large groups (lipid derivatives, shikimic acid derivatives, norisoprenoids and terpenes) were determined with good reproducibility. Important aroma compounds, such as cis-rose oxide or wine lactone were detected in non-Muscat grapes.

Acids↗
PubMed2001

Countercurrent supercritical fluid extraction and fractionation of alcoholic beverages.

A procedure for the recovery of aromatic extracts from distilled alcoholic beverages by means of a countercurrent supercritical fluid extraction (CC-SFE) on a pilot plant scale is studied. The beverage is directly in contact with the carbon dioxide current in a packed column, and the extracts are recovered in two different fractionation cells, where the depressurization occurs. The proposed method allows the selective extraction of aromatic components of the brandy flavor, rendering a high-value concentrated extract and a colored residue without brandy aroma. The content in ethanol of the aromatic extract can be modified by tuning the extraction/fractionation conditions, rendering from 15 to 95% recovery. The effect of the main variables, including extraction pressure and quality of extracting CO(2), has been tested.

Alcoholic Beverages↗
PubMedDate not supplied

Gas chromatographic determination of fentanyl and its analogues in human plasma.

There is currently no published chromatographic assay for the fentanyl family of analgesics. This study reports the development of a sensitive, precise, and accurate gas chromatographic method for the determination of fentanyl and its analogues in human plasma. Sensitivity attained for fentanyl and sufentanil was 0.1 ng/mL plasma with an average coefficient of variation of 4.5%. Calibration curve correlation coefficients of 0.99% or greater were consistently obtained. Average recovery of drug into the final extract exceeded 80% and was independent of fentanyl concentration. The required degree of specificity was obtained by selective extraction, use of the nitrogen/phosphorous detector, and chromatographic resolution. This method appears suitable for clinical studies of fentanyl and its derivatives in man.

Alfentanil↗
PubMed1984

Passive stiffness of rat cardiac myocytes.

Intact single cells were isolated from adult rat hearts by enzymatic digestion and suspended in 0.25 mM Ca++ Tyrode's solution. Quiescent, clearly striated rodlike cells were selected for study of the elastic properties of the cells at various stages of membrane and myofilament extraction. Selected cells were placed in a relaxing solution (pCa + 9, 10 mn EGTA) and then each end gently pulled into the tip of a closely fitting suction micropipette for attachment to a force transducer and length perturbation driver. This procedure was performed in low Ca++ to prevent Ca++ loading of the cell during attachment and at room temperature to prevent chemical skinning of the cell. Stiffness was measured by applying a 5-Hz sinusoidal length perturbation (5 percent L0) to one end of the cell while measuring the induced tension change at the other. The ratio of sinusoidal tension change to applied length change (stiffness) was determined for each cell over a length range of about 1-1.3 L0 before removal of the contractile filaments and up to 3.0 L0 after treatment with 0.6 M KI. The stiffness-length relation was measured first in relaxing solution and then in 0.25 mM Ca++ Tyrode's. If spontaneous contractions or contracture occurred the cell was rejected. If the cell remained quiescent and relaxed it was treated again with relaxing solution and 1 percent Triton X-100 to remove the membranes. The stiffness-length relation was again measured and then the cell was superfused with 0.47 M KCl/10 mM pyrophosphate solution to remove the myosin filaments.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗