Membranes for measuring Low Molecular Weights by Osmotic Pressure

Nature ◽  
1967 ◽  
Vol 213 (5077) ◽  
pp. 692-693 ◽  
Author(s):  
J. R. H. WAKE ◽  
A. M. POSNER
Keyword(s):  
Osmotic Pressure ◽  
Molecular Weights

scholarly journals OSMOTIC PRESSURE STUDY OF PROTEIN FRACTIONS IN NORMAL AND IN NEPHROTIC SUBJECTS

1939 ◽  
Vol 69 (6) ◽  
pp. 819-831 ◽  
Author(s):  
Jaques Bourdillon
Keyword(s):  
Osmotic Pressure ◽  
Normal Serum ◽  
The Other ◽  
Protein Fractions ◽  
Molecular Weights ◽  
Other Hand ◽  
Normal Albumin

In serum of patients with nephrosis both albumin and globulin showed by osmotic pressure nearly double the molecular weights of normal albumin and globulin. In the urines of such patients, on the other hand, both proteins showed molecular weights lower even than in normal serum. The colloidal osmotic pressures were measured by the author's method at such dilutions that the van't Hoff law relating pressures to molecular concentrations could be directly applied. For the albumin and globulin of normal serum the molecular weights found were 72,000 and 164,000 respectively, in agreement with the weights obtained by other methods.

THE INFLUENCE OF MEMBRANE PREPARATION ON THE OSMOTIC PRESSURE OF POLYVINYL ACETATE IN ACETONE

1946 ◽  
Vol 24b (4) ◽  
pp. 150-166 ◽  
Author(s):  
R. E. Robertson ◽  
R. McIntosh ◽  
W. E. Grummitt
Keyword(s):  
Sodium Hydroxide ◽  
Osmotic Pressure ◽  
Cell Volume ◽  
Polyvinyl Acetate ◽  
Membrane Surface ◽  
Membrane Preparation ◽  
Adequate Explanation ◽  
Full Account ◽  
Molecular Weights ◽  
Large Ratio

A full account of the experimental procedures used to determine the number average molecular weights of a series of polyvinyl acetates is given. Adsorption of polyvinyl acetate on a cellophane membrane is demonstrated. The importance of this phenomenon is increased when cells of large ratio of membrane surface to cell volume are used. The presence of small amounts of sodium hydroxide in the membrane eliminates detectable adsorption and alters the osmotic pressure values. This change does not appear to be due to imperfect semipermeability of the membranes, and no adequate explanation of the phenomenon has been as yet discovered.

THE NUMBER OF SUBUNITS IN THE MOLECULE OF HORSE HEMOGLOBIN

1956 ◽  
Vol 34 (4) ◽  
pp. 411-425 ◽  
Author(s):  
M. E. Reichmann ◽  
J. Ross Colvin
Keyword(s):  
Light Scattering ◽  
Osmotic Pressure ◽  
Performic Acid ◽  
Approach To Equilibrium ◽  
Salt Solutions ◽  
Covalent Bonds ◽  
Molecular Weights ◽  
Equilibrium Sedimentation ◽  
Hemoglobin Molecule ◽  
Ph Range

The molecular weights of horse hemoglobin, horse globin, and performic acid oxidized horse globin were determined by osmotic pressure, by an approach to equilibrium sedimentation, and by light scattering (except hemoglobin) at pH 1.5 to 2.5 in 0.05 M NaCl. Sedimentation coefficients were determined for these materials over the same pH range and electrophoretic analyses were made from pH 1.5 to 4.0. The results show that in dilute salt solutions below pH 2.5 horse hemoglobin dissociates to four subunits all approximately equal in mass but at least two of which differ electrokinetically and therefore in composition. The subunits are probably held together in the native hemoglobin molecule only by non-covalent bonds.

Equation for osmotic pressure of serum protein (fractions)

2004 ◽  
Vol 96 (2) ◽  
pp. 762-764 ◽  
Author(s):  
Johan Ahlqvist
Keyword(s):  
Molecular Weight ◽  
Regression Analysis ◽  
Osmotic Pressure ◽  
Serum Protein ◽  
Protein Fractions ◽  
Fibrinogen Concentration ◽  
Nonlinear Regression Analysis ◽  
Molecular Weights ◽  
Wide Range ◽  
Better Than

The colloid or protein osmotic pressure (Π) is a function of protein molarity (linear) and of Donnan and other effects. Albumin is the major osmotic protein, but also globulins influence Π. Equations based on concentrations of albumin and nonalbumin (globulin concentration + fibrinogen concentration) protein approximate Π better than albumin alone. Globulins have a wide range of molecular weights, and a 1956 diagram indicated that Π of globulin fractions decreased in the order α1-, α2-, β-, and γ-globulin. The molecular weight of the serum protein fractions had been extrapolated, so van't Hoff's law and nonlinear regression analysis of the curves permitted expression of the diagram as an equation: [Formula: see text], where Πs,Ott,2°C,cmH2O is Π of serum at 2°C (in cmH2O) computed from the 1956 diagram, Ctot is the concentration (g/l) of total protein in serum, and xalb, xα1, xα2, xβ, and xγ are the fractions of albumin, α1-, α2-, β-, and γ-globulin, respectively. At one and the same concentration of fractions, Π“Ott” decreases in the order α1-globulin, albumin, α2-globulin, β-globulin, and γ-globulin.

The Structure of Neoprene. I. The Molecular-Weight Distribution of Neoprene Type GN

1949 ◽  
Vol 22 (3) ◽  
pp. 680-689
Author(s):  
W. E. Mochel ◽  
J. B. Nichols ◽  
C. J. Mighton
Keyword(s):  
Molecular Weight ◽  
Natural Rubber ◽  
Osmotic Pressure ◽  
Molecular Weight Distribution ◽  
Weight Distribution ◽  
Distribution Curve ◽  
Pressure Measurements ◽  
Dilute Solution ◽  
Molecular Weights ◽  
Good Agreement

Abstract Polychloroprene rubber (Neoprene Type GN) was fractionated by partial precipitation from dilute solution in benzene and the fractions were examined both osmotically and viscometrically in benzene solutions. The molecular-weight distribution curve for Neoprene Type GN based on osmotic pressure measurements shows a pronounced maximum at 100,000, but has a long extension to molecular weights of over one million, indicating the presence of branched or cross-linked material which is still soluble. The uniformity is somewhat less than that of sol natural rubber, while in shape the Neoprene distribution curve resembles more closely that of peptized natural rubber than fresh sol rubber. Observed variations in the slopes of the π/c vs. c and the ηsp/c vs. c curves also indicate the presence in solution of complex, branched and (or) cross-linked molecules. Calibration of the intrinsic viscosity-molecular weight relationship by osmotic pressure measurements gave good agreement with the equation: [η]=KMa, where K=1.46×10−4 and a=0.73.

COPOLYMERS OF STYRENE AND CHLORANIL

1950 ◽  
Vol 28b (8) ◽  
pp. 507-513 ◽  
Author(s):  
J. W. Breitenbach ◽  
A. J. Renner
Keyword(s):  
Osmotic Pressure ◽  
Benzoyl Peroxide ◽  
Hydrogen Bromide ◽  
Chlorine Content ◽  
Pressure Measurements ◽  
Carbonyl Groups ◽  
Molecular Weights

The copolymerization of styrene and chloranil in the presence of benzoyl peroxide is described. The molecular weights of the copolymers were determined by osmotic pressure measurements and found to be between 9,000 and 30,000 for the different fractions; their chlorine content is between 37 and 38.2%. The copolymerization occurs with the carbonyl groups of the chloranil, transforming it into a derivative of tetrachlorohydroquinone. This reaction has been verified by degradation of the copolymers with hydrogen bromide.

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