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PubMed1981

Concentration of human respiratory syncytial virus using ammonium sulfate, polyethylene glycol or hollow fiber ultrafiltration.

Human respiratory syncytial virus was concentrated by polyethylene glycol or ammonium sulfate precipitation as well as by hollow ultrafiltration. Recoveries obtained were respectively 49.4%, 47.7%, and 75.2%; however, further analysis of these results by resuspension experiments showed that all the infectivity could be recovered from the different concentrates. The protein content of polyethylene glycol concentrates was much lower than those of ammonium sulfate or hollow fiber ultrafiltration. Electron microscopy revealed that the morphological integrity of virus particles was unaffected by the concentration methods used. Purified virus was obtained when polyethylene glycol concentrates were centrifuged through two successive density gradients.

Ammonium Sulfate↗
PubMed1992

Atrial natriuretic factor and concomitant hormonal, hemodynamic and renal function changes after slow continuous ultrafiltration.

We treated a patient with refractory biventricular heart failure, dilutional hyponatremia and prerenal azotemia, by means of ultrafiltration. After ultrafiltration, gas exchange and cardiac output improved, with concomitant reduction of systemic and pulmonary vascular resistances. Despite a decrease of right atrial and wedge pressure, atrial natriuretic factor rose and plasma renin activity decreased.

Atrial Natriuretic Factor↗
PubMed1984

Interactions of lens proteins. Ultrafiltration is unsuitable to detect self- or mixed-association.

Crystallins from calf lens were subjected to ultrafiltration through an Amicon XM-300 membrane to determine whether specific interactions between identical proteins (self-association) or different proteins (mixed-association) could be detected and quantified. Single crystallins at different concentrations, simple mixtures and total lens extracts were studied separately. alpha-Crystallin (Mr 800 000) is nearly fully retained (greater than 95%) by XM-300. Retention of beta-crystallins (Mr 50 000-200 000) is found to be much higher than expected from their molecular weights. Ultrafiltration of gamma-crystallin (Mr 20 000) solutions of 1.0-22.6 g/l shows that retention increases as a function of protein concentration. In solutions of single crystallins, self-association effects could not be separated from concentration polarization effects at the membrane surface. In mixtures of crystallins, mixed-association could not be separated from self-association, concentration polarization and excluded volume effects on self-association.

Animals↗
PubMed1992

Measurement of free amino acid levels in ultrafiltrates of blood plasma by high-performance liquid chromatography with automatic pre-column derivatization.

Although there are many techniques available for the analysis of amino acids, deproteinization is still one of the major problems in the analysis of amino acids in physiological fluids. The method used to prepare the plasma and to remove the plasma protein has a marked effect on the final results. The most widely used method of deproteinization is precipitation with 5-sulphosalicyclic acid followed by centrifugation to remove the precipitated protein. We have not had success in using this deproteinization agent for the analysis of plasma amino acids by a high-performance liquid chromatographic method with automatic pre-column o-phthaldialdehyde-3-mercaptopropionic acid and 9-fluorenylmethyl chloroformate derivatization because of the adverse effect of the sulphosalicyclic acid supernatant on the quantitation and separation. Ultrafiltration was used as an alternative method for the preparation of plasma samples in this experiment. The results were satisfactory for the analysis of plasma amino acids in 1500 samples during a period of four years. Some factors that might influence the results of the ultrafiltration were investigated.

Amino Acids↗
PubMed1995

Determination of free concentration of ropivacaine and bupivacaine in blood plasma by ultrafiltration and coupled-column liquid chromatography.

A coupled-column liquid chromatographic method for determining the free concentration of ropivacaine and bupivacaine in blood plasma was developed. Following adjustment of the temperature and pH, the plasma samples were ultrafiltrated. Ropivacaine or bupivacaine in the ultrafiltrate was determined by direct injection into a coupled-column liquid chromatographic system, consisting of one reversed-phase and one ion-exchange column. The system was highly selective. Ropivacaine and bupivacaine were detected by UV at 210 nm. The limit of determination was 10 nM and the inter-assay precision at a concentration level of about 100 nM was 6% (R.S.D., n = 30) for ropivacaine and 7% (R.S.D., n = 30) for bupivacaine.

Amides↗
PubMed1995

Stability of cisplatin and its monohydrated complex in blood, plasma and ultrafiltrate--implications for quantitative analysis.

The stability of cisplatin and its monohydrated complex has been studied in blood, plasma and plasma ultrafiltrate at 37 degrees C (pH 7.4). Intact cisplatin and the monohydrated complex were determined by liquid chromatography with post-column derivatization. The half lives for cisplatin and the monohydrated complex were 1.43 +/- 0.03 h (SEM) and 0.36 +/- 0.03 h (SEM), respectively, in blood and 0.88 +/- 0.05 h (SEM) and 0.26 +/- 0.02 h (SEM), respectively, in plasma. The compounds were unstable at -25 degrees C (t1/2 for cisplatin was 52 +/- 5 h (SEM) and for the monohydrated compound 26 +/- 2 h (SEM)), but at -70 degrees C both compounds were stable for at least 3 weeks. The monohydrated complex was found to be formed to a small extent when cisplatin was added to plasma (37 degrees C, pH 7.4). A sampling procedure using centripetal ultrafiltration of whole blood was evaluated and found applicable if the samples were stored at 0 degree C and ultracentrifuged within 1 h.

Cisplatin↗
PubMed1995

High-performance liquid chromatographic determination of cis-dichlorodiammineplatinum(II) in plasma ultrafiltrate.

A reproducible, simple and sensitive high-performance liquid chromatographic method was described for the quantitative analysis of cis-diamminedichloroplatinum(II) (CDDP) in ultrafiltrate plasma in the presence of nickel chloride as internal standard. CDDP and the internal standard were chelated by exchange with diethyldithiocarbamate. After derivatization, the mixture was directly injected into the column. Chromatography was performed on an Ultrasphere column and the eluent measured spectrophotometrically at 260 nm for CDDP and at 250 nm for the internal standard. The peak area ratio of CDDP to the internal standard varied linearly with concentration over the range 0.05-10 micrograms ml-1. Precision and reproducibility were both excellent and the limit of quantification was 0.03 micrograms ml-1 using only 0.5 ml of ultrafiltrate. The present method, without extraction, should be entirely automated. This assay may be suitable for therapeutic drug monitoring in patients receiving CDDP.

Antineoplastic Agents↗
PubMed2004

Simultaneous removal of chlorinated aromatic hydrocarbons, nitrate, and chromate using micellar-enhanced ultrafiltration.

Feasibility of micellar-enhanced ultrafiltration for the mixed waste that is consisted of chlorinated aromatic hydrocarbons, nitrate, and chromate was investigated using a cationic surfactant. The co-presence of nitrate and chromate did not significantly affect the removal of chlorobenzenes, and the co-presence of chlorobenzenes did not affect the removal of nitrate and chromate because chlorobenzenes were solubilized at the hydrophobic interior of the micelles by hydrophobic interaction, but nitrate and chromate were bound to the outer shell by electrostatic interaction. Micellar-enhanced ultrafiltration can be applied to treat the mixed wastes.

Chromates↗
PubMed2006

Multielement characterization of metal-humic substances complexation by size exclusion chromatography, asymmetrical flow field-flow fractionation, ultrafiltration and inductively coupled plasma-mass spectrometry detection: a comparative approach.

The use of three different separation techniques, ultrafiltration (UF), high performance size exclusion chromatography (HPSEC) and asymmetrical flow field-flow fractionation (AsFlFFF), for the characterization of a compost leachate is described. The possible interaction of about 30 elements with different size fractions of humic substances (HS) has been investigated coupling these separation techniques with UV-vis absorption spectrophotometry and inductively coupled plasma-mass spectrometry (ICP-MS) as detection techniques. The organic matter is constituted by a polydisperse mixture of humic substances ranging from low molecular weights (around 1kDa) to significantly larger entities. Elements can be classified into three main groups with regard to their interaction with HS. The first group is constituted by primarily the monovalent alkaline metal ions and anionic species like B, W, Mo, As existing as oxyanions all being not significantly associated to HS. The second group consists of elements that are at least partly associated to a smaller HS size fraction (such as Ni, Cu, Cr and Co). A third group of mainly tri- and tetravalent metal ions like Al, Fe, the lanthanides, Sn and Th are rather associated to larger-sized HS fractions. The three separation techniques provide a fairly consistent size classification for most of the metal ions, even though slight disagreements were observed. The number-average molecular weight (Mn), the weight-average molecular weight (Mw) and the polydispersity (rho) parameters have been calculated both from AsFlFFF and HPSEC experiments and compared for HS and some metal-HS species. Differences in values can be partly explained by an overloading effect observed in the AsFlFFF experiments induced by electrostatic repulsion effects in the low ionic strength, high pH carrier solution. Size information obtained from ultrafiltration is not as resolved as for the other methods. Molecular weight cut-offs (MWCO) of the individual filter membranes refer to globular proteins and molecular weight information may therefore, deviate from that given by the other methods after calibration with polystyrene sulfonate (PSS) standards.

Chromatography, Gel↗
PubMed2005

Validation of 5 routine assays for serum free testosterone with a candidate reference measurement procedure based on ultrafiltration and isotope dilution-gas chromatography-mass spectrometry.

BACKGROUND/METHOD: The analytical validity of free testosterone (FTe) analog immunoassays is subject to much controversy. We revisited the validation of 4 analog assays and 1 FTe calculation procedure with a metrologically traceable reference measurement procedure (RMP) based on ultrafiltration and isotope dilution-mass spectrometry for direct measurement of Te in the ultrafiltrate. To this end, we performed split-sample measurements of 40 male sera. RESULTS: Deming regression showed that 3 of the immunoassays had moderate to good correlation (0.8474 < or = r < or = 0.9241) with the RMP; however, the slope was markedly below 1. The FTe calculation procedure was in good agreement with this result. The Sy/x values for all assays were higher than the combined imprecision values, which indicate their susceptibility to matrix-related effects. CONCLUSIONS: The study demonstrated substantial differences in analytical quality of FTe assays; however, the results suggested that after extending the validation with a larger variety of samples, recalibration of some analog assays might be worth further investigation.

Adult↗
PubMed2006

Theoretical analysis and verification of concentration distribution model in the ultrafiltration process.

Based on the assumed flat model, Navier-Stokes equation for two-dimensional laminar flow fluid and the theory for diffusion and mass transfer, we obtained theoretical results with regarding to the concentration distribution in separation process by mass transfer model in the ultrafiltration process. Through theoretical analysis and experimental verification of concentration distribution, it was known that this model could not only preferably describe the concentration distribution of ultrafiltration process but also forecast concentration polarization phenomenon.

Models, Theoretical↗
PubMed2004

Comparison between ultrafiltration and trichloroacetic acid precipitation method for concentration of Staphylococcus aureus enterotoxin in dairy samples.

Staphylococcus aureus enterotoxin that may be contained at low concentrations in milk and dairy products can cause food poisoning. To detect this enterotoxin at low concentrations, samples should be concentrated. We evaluated the performance of centrifugal ultrafiltration method (UF) in comparison with trichloroacetic acid precipitation method (TCA) for the concentration of S. aureus enterotoxin in milk and dairy products. S. aureus enterotoxin A (SEA) were added at various concentrations to ultra high-temperature heating process (UHT) milk, UHT concentrated skim milk, UHT skim milk powder, low heat-treated (LH) skim milk powder, and raw milk. SEA was concentrated by TCA and UF once a day on a total of 3 days by different researchers to prepare test solutions. The fluorescence value (TV) of test solutions was determined using an immunofluorescence autoanalyzer (miniVIDAS), and the linearity and slope of the regression line, relative standard deviation (RSD(RW)) at each added concentration, detection limit (DL), quantification limit (QL), and the recovery rate by each concentration method were obtained according to the guidelines of the International Conference on Harmonization (ICH). The slope of the regression line obtained by UF was steeper than that by TCA for all dairy samples excluding LH (74 degrees C, 20 s) skim milk powder. RSDRW, DL, and QL obtained by UF were comparable to or more excellent than those obtained by TCA. The procedure of UF was simpler than that of TCA. The recovery rate and rapidity were similar between the two methods. The DL and QL of enterotoxins other than SEA in dairy products by UF or TCA were estimated based on the DL and QL of SEA. In this estimation, consideration was given to reactions between each enterotoxin and its antibody, and also to the immunoactivity maintenance rate of each enterotoxin after addition of trichloroacetic acid in TCA. The estimated values were similar to those obtained by experiments using enterotoxin C1 (SEC1). UF using a centrifugal ultrafiltration membrane can be more readily performed and similar to or more reliable than TCA. UF combined with a miniVIDAS can be used for quantitative routine analysis.

Animals↗
PubMed2004

Separation and purification of benzylpenicillin produced by fermentation using coupled ultrafiltration and nanofiltration technologies.

The purpose of this study was to evaluate the capacity of using coupled ultrafiltration-nanofiltration technologies for separation and purification of benzylpenicillin (BP). More specifically, we verified the efficiency of three ultrafiltration (UF) membranes (cut-off of 5000, 30,000 and 100,000 Da) to remove impurities that cause stable emulsion during the chemical extraction of the antibiotic. We also tested the effectiveness of a nanofiltration (NF) membrane (cut-off of 300 Da) to concentrate the benzylpenicillin recovered from permeates and to decrease the osmotic pressure by reducing the ionic charge of the broth. Results have shown that high recovery (89.0-91.0%) can be obtained in permeate generated by the 30,000 and 100,000 UF membranes, but a slight emulsion will be formed during phase separation. With the 5000 UF membrane, lower recovery is obtained (81.0%) but no emulsion is produced, leading to a high solvent extraction yield (94.6%). The nanofiltration of 30,000 and 100,000 UF permeates leads to very high recovery (98.0%), but stable emulsions are formed, reducing the chemical extraction yield (80.0-82.6%). For the nanofiltration of 5000 UF permeate, excellent recovery of the antibiotic is noted (97.4%) leading to high extraction yield (92.4%) with no emulsion formed. Diafiltration step should be applied during UF procedure in order to increase the antibiotic recovery in the generated permeates.

Fermentation↗
PubMed2006

Simultaneous separation of acid and basic bioactive peptides by electrodialysis with ultrafiltration membrane.

beta-Lactoglobulin (beta-lg), one of the major whey components, can release by enzymatic hydrolysis different bioactive peptidic sequences according to the enzyme used. However, these protein hydrolysates have to be fractionated to obtain peptides in a more purified form. The aim of the present work was to evaluate the feasibility of separating peptides from a beta-lg hydrolysate using an ultrafiltration (UF) membrane stacked in an electrodialysis (ED) cell and to study the effect of pH on the migration of basic/cationic and acid/anionic peptides in the ED configuration. Electrodialysis with ultrafiltration membrane (EDUF) appeared to be a selective method of separation since amongst a total of 40 peptides in the raw hydrolysate, only 13 were recovered in the separated adjacent solutions (KCl 1 and KCl 2). Amongst these 13 migrating peptides, 3 acid/anionic peptides migrated only in one compartment (KCl 1), while 3 basic/cationic peptides migrated only in the second compartment (KCl 2) and that whatever the pH conditions of the hydrolysate solution. Furthermore, the highest migration was obtained for the ACE-inhibitory peptide beta-lg 142-148, with a value of 10.75%. The integrity of the UF membrane was kept and EDUF would minimize the fouling of UF membrane.

Animals↗
PubMed2005

Humic substance-enhanced ultrafiltration for removal of cobalt.

It is well known that the membrane separation process combined with surfactant micelle (micellar-enhanced ultrafiltration) or polyelectrolyte (polyelectrolyte-enhanced ultrafiltration) can remove heavy metal ions or radionuclides effectively. However, the complexing agent, surfactant or polyelectrolyte remained in effluent is a serious disadvantage of these methods. In this study, humic substances (HS) were used as complexing agents instead of synthetic chemicals. The HS are sorts of natural organic matters and their functional groups such as carboxyl and phenyl groups can bind with the cation and form complexes. The effects of HS concentration and pH on the removal of cobalt were investigated. At the HS concentration of 3g/L and pH of 6, over 95% of cobalt was removed by regenerated cellulose membrane with molecular weight cut-off (MWCO) of 3000. As the HS concentration increased, the removal of cobalt was also enhanced because of the increase in binding sites (functional groups). The removal of cobalt increased from 72.5% to 97.5% as pH increased from 4 to 8 at the HS concentration of 3g/L. It resulted from the more deprotonation of functional groups in humic acid at higher pH.

Cobalt↗
PubMed2006

Removal of chromium from aqueous solution using cellulose acetate and sulfonated poly(ether ether ketone) blend ultrafiltration membranes.

A process for purifying aqueous solutions containing heavy and toxic metals such as chromium has been investigated. Chromium salts are largely used in various industries including leather-manufacturing industry. Ultrafiltration processes are largely being applied for macromolecular and heavy metal ion separation from aqueous streams. Cellulose acetate and sulfonated poly(ether ether ketone) blend ultrafiltration membranes were prepared by precipitation phase inversion technique in 100/0, 90/10, 80/20 and 70/30% polymer blend compositions and subjected to the rejection of chromium at different concentrations such as 200, 400, 600, 800 and 1000 ppm with a water-soluble macroligand (polyvinylalcohol). Factors affecting the percentage rejection and permeate flux such as pH, concentration of solute, concentration of PVA, transmembrane pressure and composition of blend membranes were investigated. It was found that percentage rejection improved at a pH 6 and a macroligand concentration of 2 wt.%. The transmembrane pressure and concentration of solute also have an effect on the separation and product rate efficiencies of the blend membranes.

Alcohols↗
PubMed2004

The development and application of a surface plasmon resonance-based inhibition immunoassay for the determination of warfarin in plasma ultrafiltrate.

Warfarin is the most widely prescribed oral anticoagulant for the management of a wide variety of thromboembolic disorders such as atrial fibrillation and deep vein thrombosis. A panel of warfarin-protein conjugates were produced and characterised and subsequently used for the production of monoclonal antibodies to warfarin. Following characterisation, the monoclonal antibodies were used in the development of a surface plasmon resonance-based inhibition immunoassay for the determination of the physiologically active 'nonprotein'-bound fraction of the drug in plasma ultrafiltrate. The inhibition immunoassay was compared with an existing high-performance liquid chromatography (HPLC) chromatographic technique for the determination of warfarin in plasma ultrafiltrate, and an excellent correlation was achieved between the two independent analytical techniques. The ligand-binding capacity and stability of various immobilised ligands were also compared. The BIACore-based inhibition immunoassay demonstrated an assay precision range of approximately 4-250 ng/ml, which is within the clinical range and demonstrated good reproducibility and robustness.

Animals↗
PubMed2005

Modification of the ultrafiltration technique to overcome solubility and non-specific binding challenges associated with the measurement of plasma protein binding of corticosteroids.

Plasma protein binding (PPB) methodology suitable for application in the lead optimisation of a corticosteroid series known to demonstrate non-specific binding (NSB) and poor solubility has been established. The method involved a modification to standard ultrafiltration (UF) techniques. In parallel with each experimental plasma sample, a control plasma sample was also processed by ultrafiltration. The retentate from experimental and control plasma samples were mixed back into the filtrate of the partner sample. The resulting regenerated plasma samples, one representing the experimental filtrate and one representing the experimental retentate, were then analysed by LC/MS/MS. Varying degrees of NSB were demonstrated with a number of corticosteroids, and this effect was eliminated using the modified method. Validation using a panel of established corticosteroids showed good agreement with published PPB figures. The published PPB figure for fluticasone propionate (FP) was, however, found to be an underestimate, and this was subsequently confirmed, at clinically relevant plasma concentrations, to be 99.3%. The modified method was particularly suited to lead optimisation because it provided samples in a consistent matrix compatible with standard high throughput LC/MS/MS analysis.

Adrenal Cortex Hormones↗