Big Chemical Encyclopedia

Chemical substances, components, reactions, process design ...

Articles Figures Tables About

Dialysis membranes and

In one version of the urea electrode, shown in Figure 11.16, an NH3 electrode is modified by adding a dialysis membrane that physically traps a pH 7.0 buffered solution of urease between the dialysis membrane and the gas-permeable... [Pg.484]

FIGt 22-48 Transport mechanisms for separation membranes a) Viscous flow, used in UF and MF. No separation achieved in RO, NF, ED, GAS, or PY (h) Knudsen flow used in some gas membranes. Pore diameter < mean free path, (c) Ultramicroporoiis membrane—precise pore diameter used in gas separation, (d) Solution-diffusion used in gas, RO, PY Molecule dissolves in the membrane and diffuses through. Not shown Electro-dialysis membranes and metallic membranes for hydrogen. [Pg.2025]

The history of glucose enzyme electrodes starts with the first device developed in 1962 by Clark and Lyons from the Children Hospital in Cincinnati [3], Their first device relied on a thin layer of GOx entrapped over an oxygen electrode (via a semipermeable dialysis membrane), and monitoring the oxygen consumed by the enzyme-catalyzed reaction ... [Pg.81]

A stopped flow approach can be employed using dialysis sampling which allows effective transport of low molecular weight components from the sample across the dialysis membrane and hence the dialysate will accurately reflect the composition of the sample. [Pg.139]

Herve, S. Paukku, R. Paasivirta, J. Heinonen, R Sodergren, A. 1991, Uptake of organochlo-rines from lake water by hexane-tilled dialysis membranes and by mussels. Chemosphere 22 997-1001. [Pg.206]

Graph used to calculate the point of no net flux for dopamine (DA). Using regression analysis, the extracellular concentration of DA is estimated via the difference method [the DA concentration in the perfusate minus the concentration of DA in the dialysate] plotted against the DA concentration in the perfusate. Values above the zero on the y-axis indicate diffusion to the brain, whereas values below the zero indicate diffusion from the brain. The zero point on the y-axis represents a steady state, at which no net flux of DA occurs across the dialysis membrane and represents the extracellular concentration of DA on the x-axis. Figure from Parsons, L.H., Justice, J.B., Jr. (1994). Quantitative approaches to in vivo brain microdialysis. Crit Rev Neurobiol. 8(3) 189-220... [Pg.229]

Remove the required number of strips of dialysis membrane and rinse them well with water to remove all traces of ethanol. [Pg.14]

Online dialysis and subsequent trace enrichment has been further described for isolation/purification of flumequine residues from fish muscle (203), or oxolinic acid and flumequine from chicken liver (193) and salmon muscle (204). This involves online purification by diphasic dialysis membrane and trapping of the analytes onto a liquid chromatographic preconcentration column (reversed-phase Ci8 or polymeric), rinsing of the coextracted materials to waste, and finally flushing of die concentrated analytes onto the analytical column. [Pg.957]

PROBLEM 11.28 What is the difference between a dialysis membrane and the typical semipermeable membrane used for osmosis ... [Pg.461]

Gajovic et al. [64] L-malate Fruits, fruit juices, ciders and wines NAD(P)+-dependent L-malate dehydrogenase oxaloacetate decarboxylating with salicylate hydroxylase (SHL)/ in gelatine membrane sandwiched between a dialysis membrane and a PET membrane Clark-electrode ... [Pg.268]

Inaba et al. [2] d-Alanine Fish sauces D-Amino acid oxidase (d-AAOx) and pyruvate oxidase (PyOx)/PyOx is immobilised on a membrane and sandwiched between dialysis membrane and Teflon membrane of the oxygen electrode Oxygen electrode ... [Pg.272]

Cut out a disk of about 5-8 mm in diameter and about 1mm in thickness of the agarized gel stratified on the Petri dish, remove from it and sandwich between a dialysis membrane and the gas permeable membrane of the Clark electrode secure the whole assembly to the head of the electrode by means of an O-ring. [Pg.1035]

Assemble 5 mg (dry weight) of thermostated algae on the Clark electrode by a dialysis membrane and a special O-ring, which have the same dimensions of flow cell. A black cloth protected all. [Pg.1036]

The membrane separation processes described above represent the bulk of the industrial membrane separation industry. Another process, dialysis, is not used industrially but is used on a large scale in medicine to remove toxic metabolites from blood in patients suffering from kidney failure. The first successful artificial kidney was based on cellophane (regenerated cellulose) dialysis membranes and was developed in 1945. Over the past 50 years, many changes have been made. Currently, most artificial kidneys are based on hollow-fiber membranes formed into modules having a membrane area of about 1 m2 the process is illustrated in Figure 1.7. Blood is circulated through the center of the fiber, while isotonic... [Pg.11]

Goodwin et al. [82] determined trace sulphides in turbid waters by a gas dialysis-ion chromatographic method. The sulphide is converted to hydrogen sulphide which is then isolated from the sample matrix by diffusion through a gas dialysis membrane and trapped in a dilute sodium hydroxide solution. A 200pL portion of this solution is injected into an ion chromatograph for determination with an electrochemical detector. Detection limits were >1.9ng/mL... [Pg.81]

Dialysis A purified protein is in a Hepes (7V-(2-hydroxyethyl)piperazine-A/ -(2-ethanesulfomc acid)) buffer at pH 7 with 500 mM NaCl. A sample (1 mL) of the protein solution is placed in a tube made of dialysis membrane and dialyzed against 1 L of the same Hepes buffer with 0 mM NaCl. Small molecules and ions (such as Na+, Cl-, and Hepes) can diffuse across the dialysis membrane, but the protein cannot. [Pg.35]

Li et al. [37-39] described the use of the bacterial species Bacillus subtilis and Bacillus licheniformis entrapped between a polycarbonate membrane and a Teflon-covered DO probe. The differences between the steady-state signals before and after exposure to the test samples were used as a measure of the sample BOD levels. Riedel et al. [32-33] described the use of the yeast Trichosporon cutaneum, or both T. cutaneum and B. subtilis, sandwiched between a dialysis membrane and a polyethylene-covered DO probe. In these cases, the sensor response times were speeded up by measuring the initial rates of change of the signals. In this way, measurements could be made within 30 s rather than within 15-20 min for the steady-state approach [33]. [Pg.199]

Norris RLG, Ahokas JT, Ravenscroft PJ (1982) Determination of unbound fraction of disopyramide in plasma a comparison of equilibrium dialysis, ultrafiltration through dialysis membranes and ultrafree anticonvulsant drug filters. J Pharmacol Methods 7(1) 7—14... [Pg.480]

There is evidence that hyphae from germinating spores of AM fungi secrete an Myc factor that enables plants to accept AM fungi. The factor can diffuse across a dialysis membrane and its molecular weight is estimated to be less than 3.5 kDa, but its chemical nature has not yet been revealed.72... [Pg.552]

Chloramines are dangerous for consumption when they go directly into the bloodstream. (Fortunately, normal digestive processes deactivate them). Kidney dialysis patients and fish owners need to take special care when using chloram-inated water, since chloramines go through the dialysis membranes and the fish gills. Addition of ascorbic acid, or removal by granulated activated carbon (GAC), prevent this problem. [Pg.241]

Figure 1. Mechanisms by which drugs are removed by dialysis (indicated by dialysate) or sorbent hemoperfusion. The pore structure of dialysis membranes and sorbents is the major determinant of chemical/drug size selection. Figure 1. Mechanisms by which drugs are removed by dialysis (indicated by dialysate) or sorbent hemoperfusion. The pore structure of dialysis membranes and sorbents is the major determinant of chemical/drug size selection.
D Amour P, Jobin J, Hamel L, L Ecuyer N. iPTH values during hemodialysis role of ionized calcium, dialysis membranes and iPTH assays. Kidney Int 1990 38 308-14. [Pg.1948]

Devis JC, Valus RJ, Lawrence EG. Aftinity dialysis— A method of continuous, rapid metal ion separation using Dialysis membranes and selective water-soluble polymers as extractants. Sep Sci Technol 1988 23, 10, 11 1039-1066. [Pg.324]

The biosensors were constructed with optical sensor for oxygen based on optical fibre Avaspec -Oxy (Avantes, Holland). The membrane with immobilised enzyme was attached to the electrodes with a dialysis membrane and a pipette tip. [Pg.407]

With a gelatin membrane entrapped between two dialysis membranes and containing 46 U/cm2 of enzyme, the H2O2 formation corresponds to only 110 mU/cm2, i.e., less than 1% of the initial enzyme activity (Fig. 28). This... [Pg.57]

In an externally buffered enzyme electrode (Fig. 45), substrate-free buffer is continuously pumped between the dialysis membrane and the enzyme layer (Cleland and Enfors, 1984), i.e., the sample is diluted before it reaches the enzyme. The intensity of the buffer flow may be used to adjust the measuring range and sensitivity. The configuration of the sensor permits it to be sterilized. While the membrane is protected by continuously flowing buffer, the rest of the sensor can be sterilized for 1 h in a solution of 95% ethanol and 5% H2SO4. [Pg.97]

The Ir/Pd-MOS condensator described in Section 3.1.21.1 (Winquist et al., 1985) has also been combined with urease to form a urea probe. Urease was entrapped between a dialysis membrane and an NH3-per-meable foil, the latter being separated from the MOS structure by an air gap of 0.1 mm width (Fig. 72). The measuring range was 0.01-5 mmolA, the response time being 3 min. The sensor had an operational lifetime of only 4 days. [Pg.171]

The improved PEP/pyruvate system developed by Kim and Swartz [7] yielded 350 pg mL of chloramphenicol acetyl-transferase (CAT) in the first hour of an E. coli batch reaction. The same reaction system yielded 750 pg mL CAT in 3 hours when periodically fed with amino acids, PEP, and magnesium acetate [6]. This is remarkable efficiency for a system lacking a dialysis membrane, and is a feature that weU suits robotic handling and high-throughput screening (HTS) strategies. [Pg.1075]

Figure 10. Recovery of proteins into a dialysis bag. Upon terminaticn of the IPG run, the gel strip containing the protein of interest is cut along the contours, chopped to pieces and loaded on top of a stacking gel in a preparative disc electrophoresis apparatias (here the glass tube has an inner diameter of 1.5 cm). After zone electrophoresis (usually 30-45 min at 4 C and 250 V), the protein is collected into the chamber having as a floor the dialysis membrane and as a ceiling the 5%T stacking gel, in a free liquid phase (20% sucrose in 100 mM Tris-acetate, pH 8.5) (Reproduced with permission from Ref. 48. copyright 1986, from Elsevier). Figure 10. Recovery of proteins into a dialysis bag. Upon terminaticn of the IPG run, the gel strip containing the protein of interest is cut along the contours, chopped to pieces and loaded on top of a stacking gel in a preparative disc electrophoresis apparatias (here the glass tube has an inner diameter of 1.5 cm). After zone electrophoresis (usually 30-45 min at 4 C and 250 V), the protein is collected into the chamber having as a floor the dialysis membrane and as a ceiling the 5%T stacking gel, in a free liquid phase (20% sucrose in 100 mM Tris-acetate, pH 8.5) (Reproduced with permission from Ref. 48. copyright 1986, from Elsevier).
With a gelatin membrane entrapped between two dialysis membranes and containing 46 U/cm of enzyme, the H2O2 formation corresponds to only 110 mU/cm, ie, less than 1% of the initial enzyme activity (Figure 14-19). This indicates a large excess of enzyme in the membrane. Consequently, the membrane is diffusion controlled. The low apparent activity may be attributed mainly to the diffusion resistance of the dialysis membrane for glucose. On the other hand, the measured activity of the membrane containing 46 U/cm is already about 70% of the activity used for immobilization. This value approaches that expected for pure kinetic control of the process [287], The apparent activity of urease immobilized in a cellulose triacetate membrane was found to be 66% of the initially applied enzyme activity [288]. [Pg.67]


See other pages where Dialysis membranes and is mentioned: [Pg.106]    [Pg.206]    [Pg.168]    [Pg.14]    [Pg.61]    [Pg.93]    [Pg.181]    [Pg.108]    [Pg.349]    [Pg.167]    [Pg.29]    [Pg.65]    [Pg.551]    [Pg.139]    [Pg.391]    [Pg.525]    [Pg.132]    [Pg.477]    [Pg.265]   


SEARCH



Dialysis

Dialysis membrane

© 2024 chempedia.info