Fast Membrane Osmometer as Alternative to Freezing Point and Vapor Pressure Osmometry

2008 ◽  
Vol 80 (7) ◽  
pp. 2617-2622 ◽  
Author(s):  
Alessandro Grattoni ◽  
Giancarlo Canavese ◽  
Franco Maria Montevecchi ◽  
Mauro Ferrari
Keyword(s):  
Vapor Pressure ◽  
Freezing Point ◽  
Vapor Pressure Osmometry

Limitations of methods of osmometry: measuring the osmolality of biological fluids

1993 ◽  
Vol 264 (3) ◽  
pp. R469-R480 ◽  
Author(s):  
T. E. Sweeney ◽  
C. A. Beuchat
Keyword(s):  
Vapor Pressure ◽  
Aqueous Solutions ◽  
Measurement Method ◽  
Freezing Point ◽  
Biological Fluids ◽  
Vapor Pressure Osmometry ◽  
Biological Phenomena ◽  
Solvent Systems

Osmometry is an important tool in the investigation of biological phenomena, and commercially available instruments for freezing point and vapor pressure osmometry can determine the osmolality of solutions quickly and inexpensively. However, accurate measurements of osmolality using these techniques require that the solutions have specific characteristics, and that measurements do not exceed the limitations inherent to each method or instrument. The thermodynamic principles underlying osmometry constrain the range and accuracy of each measurement method, and these must be considered in establishing the usefulness of each technique. This paper addresses the principles and limitations of routine osmometry techniques. We begin by discussing definitions of osmolality and the thermodynamic concepts of solute-solvent systems that are central to understanding osmometry of biological (i.e., aqueous) solutions. We then explore the application of various methods of measuring osmolality, the nature of errors introduced by overextension or misapplication of osmometry techniques, and the interpretation of data in the literature acquired by various methods and protocols.

Correction for loss of CO2 from blood during measurement of osmotic pressure

1978 ◽  
Vol 44 (3) ◽  
pp. 474-478 ◽  
Author(s):  
S. S. Khosla ◽  
A. B. DuBois
Keyword(s):  
Vapor Pressure ◽  
Blood Sample ◽  
Osmotic Pressure ◽  
Freezing Point ◽  
Gas Mixture ◽  
Sample Holder ◽  
Freezing Point Depression ◽  
Pressure Method ◽  
Sample Chamber

During osmolality measurement by the vapor pressure method, exposure of the blood sample to air lowers the blood CO2 content and hence osmolality. A modification of the sample holder of a vapor pressure osmometer is described allowing exposure of the blood sample to a gas mixture with known concentration of CO2 and O2 while inside the closed sample chamber. This restores its CO2 content and hence osmolality. Data are presented comparing the unmodified and modified vapor pressure method with the freezing point depression method. A table was prepared for further correction of osmolality in case the blood's PCO2 differs from that of the gas mixture.

KINETIC ASPECTS OF THE COPOLYMERIZATION OF TETRAHYDROFURAN WITH PROPYLENE OXIDE. I

1966 ◽  
Vol 44 (22) ◽  
pp. 2679-2689 ◽  
Author(s):  
L. P. Blanchard ◽  
J. Singh ◽  
M. D. Baijal
Keyword(s):  
Vapor Pressure ◽  
Propylene Oxide ◽  
Chemical Reduction ◽  
Group Analysis ◽  
Vapor Pressure Osmometry ◽  
Hydroxyl Groups ◽  
Internal Reference ◽  
Boron Fluoride ◽  
Co Catalysts ◽  
End Group

Tetrahydrofuran and propylene oxide were copolymerized in the presence of the catalyst boron fluoride ethyl ether, and various co-catalysts, such as 1,2-propanediol, 1,3-propanediol, and 1,4-butanediol. Ethylene chloride was used as a solvent and as an internal reference for analytical purposes. Reactions were carried out at 0 °C and at atmospheric pressure. Monomer concentrations were determined by vapor phase chromatography, and copolymer molecular structure analyses were carried out by physical and chemical methods including infrared spectroscopy, vapor pressure osmometry, hydroxyl end-group analysis, and chemical reduction of unsaturated linkages.The homopolymerization of tetrahydrofuran did not take place, whereas that of propylene oxide proceeded at a rapid rate. In the copolymerization of tetrahydrofuran with propylene oxide, the rate of disappearance of tetrahydrofuran was found to be independent of its concentration, but varied directly with the concentration of propylene oxide. Under similar conditions, the rate of disappearance of propylene oxide was found to be (a) proportional to the square of its concentration, and (b) inversely proportional to the concentration of tetrahydrofuran.Reactivity ratios varied between 1.3 and 1.8 for propylene oxide and between 0.1 and 0.6 for tetrahydrofuran. Molecular weights obtained by vapor pressure osmometry ranged between 460 and 740, and those obtained by hydroxyl end-group analysis ranged between 520 and 1 660. Infrared spectra confirmed the presence of hydroxyl groups and ether linkages in the copolymers prepared. Results on terminal unsaturation were negative.

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