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51.
This paper deals with the determination of the membrane mass transfer coefficient for sulfuric acid in an anion-exchange membrane NEOSEPTA-AFN. This quantity has been determined on the basis of experiments carried out in a batch dialysis cell using the method of numerical integration of the basic differential equation describing the time dependence of sulfuric acid concentration and subsequent optimization procedure. The experiments carried out made it possible to calculate the membrane mass transfer coefficient for sulfuric acid over the concentration range from 0.1 to 1.9 kmol m−3 in the external solution. 相似文献
52.
The thermodynamic parameters for the binding of dodecyl trimethylammonium bromide (DTAB) with wigeon hemoglobin (Hb) in aqueous solution at various pH and 27 °C have been measured by equilibrium dialysis and titration microcalorimetry techniques. The Scatchard plots represent unusual features at neutral and alkaline pH and specific binding at acidic pH. This leads us to analyze the binding data by fitting the data to the Hill equation for multiclasses of binding sites. The best fit was obtained with the equation for one class at acidic pH and two classes at neutral and alkaline pH. The thermodynamic analysis of the binding process shows that the strength of binding at neutral pH is more than these at other pH values. This can be related to the more accessible hydrophobic surface area of wigeon hemoglobin at this pH. The endothermic enthalpy data which was measured by microcalorimetry confirms the binding data analysis and represents the more regular and stable structure of wigeon hemoglobin at neutral pH. 相似文献
53.
Total metal concentrations were determined in the serum of 12 continuous ambulatory peritoneal dialysis (CAPD) patients and in fresh and spent CAPD fluids by electrothermal and flame atomic absorption spectrometry (ETAAS, FAAS). Concentrations of Cu in serum of CAPD patients ranged from 720 to 1780 ng cm−3, Rb from 128 to 346 ng cm−3, Al from 10 to 72 ng cm−3, Fe from 800 to 2300 ng cm−3 and Zn from 659 to 1310 ng cm−3. The accuracy of the analytical procedure was checked by the analysis of the reference material Seronom™, Trace Elements in Serum. Good agreement between the certified and determined values was obtained for Al, Cu, Fe and Zn. The data on the total metal concentrations in CAPD fluids indicated that during CAPD fluid exchange the losses of Cu from 5.0 to 35 ng cm−3, of Rb from 50 to 110 ng cm−3 and of Al from 3.0 to 14.0 ng cm−3 occurred through the peritoneal membrane. Although fresh CAPD fluids contained traces of Fe (3.0-5.0 ng cm−3), the transfer of this element took place through the peritoneal membrane into spent CAPD fluid (13.0-38.0 ng cm−3). Zn concentrations were in general lower in spent (20.0-80 ng cm−3) than in fresh CAPD fluids (∼100 ng cm−3). To follow the mechanisms of the transfer of trace elements through the peritoneal membrane of CAPD patients, fractionation of metals was carried out in spent CAPD fluids by size exclusion chromatography with UV and AAS detection, applying Superdex HR 10/30 column. The chromatographic run was followed at 278 nm and separated metal species also determined ‘off line’ in 1 cm3 fractions by ETAAS or FAAS. From the UV chromatograms and AAS analysis of trace elements in the separated fractions it was demonstrated that Cu, Al, Fe and Zn were bound to proteins and only partially to low molecular weight (LMW) species, while Rb was associated exclusively with LMW species. For characterisation of the high molecular weight (HMW) binding proteins, fractions containing trace elements were subjected to SDS-PAGE electrophoresis. Al and Fe were presumably bound to transferrin, but due to its low concentration in spent CAPD fluids, it was not possible to confirm its presence in the separated fractions. About 10% of Al and 15% of Fe corresponded to LMW species. A fraction of HMW proteins of Cu in spent CAPD fluids was most probably bound to albumin and Zn to albumin and globulins. About 50% of Cu and Zn existed in LMW proteins, while Zn was also found partially in ionic form. 相似文献
54.
The binding of 1-anilinonaphthalene-8-sulphonate (ANS) to poly(N-vinyl-2-pyrrolidone) (PVP) of molecular weight grades k30
(molecular weight 40,000) and k90 (360,000) was studied by a dialysis technique in 0·05 M phosphate buffer, pH 7·1, at different
temperatures. The intrinsic binding constant,K, was determined. The binding was favoured by negative enthalpy and positive entropy in both the systems indicating respectively
that energetic forces and hydrophobic interactions were contributing to the binding affinity. The effects of addition of urea
and palmitic acid on binding were investigated by dialysis and fluorescence techniques. The results showed that the binding
of ANS to PVP was dependent on the nature and microenvironment of the binding sites and thereby pointed out the importance
of the iceberg structure of water in the binding system. 相似文献
55.
56.
The binding of arsenic ions to cationic cetylpyridinium chloride (CPC) micelles has been investigated using the semiequilibrium dialysis (SED) technique. In SED experiments, it has been shown that CPC micelles are very effective in binding arsenic ions in the retentate. At the studied pH (pH 8), the unbound and bound arsenic exists primarily as divalent anions (HAsO42−) while CPC molecules exist as monovalent cations. Therefore, arsenic ions are bound electrostatically to the cationic micelle. The resultant colloid is large enough not to pass through the dialysis membrane, producing a rejection greater than 99.59%. The concentration of the unbound arsenic anions passing through the dialysis membrane is practically the same as the permeate concentration of these species in the analogous micellar-enhanced ultrafiltration (MEUF) experiments. Therefore, a nonlinear equilibrium model which combines thermodynamic relations, charge balance equations, and material balance equations with the Oosawa two-phase polyelectrolyte theory has been developed to correlate the binding of arsenic to CPC micelles in SED and MEUF. It was shown that the equilibrium model successfully accounts for the experimental data in both SED and MEUF in the absence and presence of monovalent (HCO31−) and divalent co-ions (HPO42−). Because of their small sizes (less than 10 nm), micelles should retain their equilibrium shapes in the presence of hydrodynamic shear typically attained in most dynamic processes. Therefore, the equilibrium model can be used to predict separation efficiencies in other ultrafiltration units such as in crossflow ultrafiltration processes. 相似文献
57.
《Analytical letters》2012,45(15):1501-1515
Abstract In vivo studies of urinary bis(2-ethylhexyl)phthalate (DEHP) levels in dogs and in non-uremic patients undergoing hemodialysis treatments for psoriasis were undertaken. Dogs were divided into 3 groups: Control, Sham-Operated, and Nephrectomized. Each dog received 225 mg DEHP per kilogram body weight via the femoral vein. Each of the non-uremic patients underwent hemodialysis therapy for 4–5 hours once a week for four consecutive weeks to treat their psoriatic condition. Specimens of 2 4 hr urine were collected and analyzed for DEHP by gas chromatography. The detection limit of DEHP in urine is 15 ng/ml. No detectable DEHP was found in the urine of all pre-injection specimens obtained from all three groups of dogs. The total urinary DEHP concentrations for the four day period were found to be 76.1 and 192.2 μg for the Control and the Sham-Operated dogs, respectively. No urine samples could be collected from the Nephrectomized dogs. DEHP levels were found in the 24 hr urine specimens from some of the non-uremic patients undergoing hemodialysis therapy. The DEHP concentrations ranged from non-detectable to 159.8 yg/24 hrs. Normal renal function seems to be necessary for the excretion of non-metabolized DEHP. 相似文献
58.
Matthias Frischmann Johanna Spitzer Michael Fünfrocken Stefan Mittelmaier Melanie Deckert Thomas Fichert Monika Pischetsrieder 《Biomedical chromatography : BMC》2009,23(8):843-851
A method was developed and validated to quantify 3,4‐dideoxyglucosone‐3‐ene in peritoneal dialysis fluids by high‐performance liquid chromatography with UV detection after derivatization with o‐phenylenediamine. The advantages of this method compared with direct HPLC analysis are (i) the possibility of quantifying 3,4‐dideoxyglucosone‐3‐ene simultaneously together with other glucose degradation products, (ii) the compatibility of the method with MS detection for unequivocal identification of the analyte and (iii) a bathochromic shift of the UV absorbance maximum which leads to higher selectivity. The validated method was used to measure 3,4‐dideoxyglucosone‐3‐ene concentrations additionally to the glucose degradation products 3‐deoxyglucosone, methylglyoxal, glyoxal, 5‐hydroxymethylfurfural, 2‐furaldehyde, formaldehyde and acetaldehyde in 19 commercial products for peritoneal dialysis. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
59.
《Analytical letters》2012,45(13):1473-1486
Abstract A method was developed for aluminium determination in dialysis fluids by graphite-tube furnace atomic absorption spectroscopy utilizing the L'vov platform. Results are reported for various kinds of dialysis fluids. In all cases accuracy and precision of the analytical procedure were ascertained. 相似文献
60.
《Analytical letters》2012,45(15):2717-2728
Abstract Linear scan cathodic stripping voltammetry at glassy-carbon based thin mercury film electrodes is a simple and inexpensive alternative for determining trace Al(III) in dialysis fluids. The efficiency of a variety of ligands (SVRS, Cupferron and Blue Black Eriochrome R) was evaluated comparing their voltamperometric response by application of a linear scan mode, after preconcentration into the mercury film electrode as Al(III) complexes. The best results were obtained when Cupferron was used as ligand, since its stripping current compares favourably in terms of sensitivity and resolution. The sharply defined cathodic peak at -1.3 V, corresponding to the reduction of the interfacial accumulated complex, could be used for quantitation. The response is linear up to 50 μg/l; correlation coefficient, 0.995. The relative standard deviation (at 20 μg/l level) is 3.5%, a detection limit of 0.5μg/l was estimated from the signal to noise characteristics of the response for 5 μg/l, which compares favourably among the reported electroanalytical methods for aluminium. We calibrated the method under conditions of use estimating the trace aluminium exposure in patients undergoing dialytic treatment. 相似文献