The average molecular weight and shape of the “polymeric acids” found in Black Trona Water from the Green River Basin |
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| Authors: | Roland E Barden Eugenia R Logan JF Branthaver Kenneth E Neet |
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| Institution: | 1. Departments of Chemistry and Biochemistry, University of Wyoming, Laramie, WY 82071, U.S.A.;2. Division of Physical Sciences, University of Wyoming Research Corporation, Laramie, WY 82071, U.S.A.;3. Department of Biochemistry, Case Western Reserve University, Cleveland, OH 44106, U.S.A. |
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| Abstract: | Macromolecular organic material, called “polymeric acids”, has been isolated from Black Trona Water by exhaustive dialysis and characterized as the sodium salt in 0.10 M sodium carbonate, pH 10, by several physico-chemical methods. Analysis by gel filtration chromatography on Sepharose-CL 6B indicates that the “polymeric acids” are polydisperse and composed of species of relatively high molecular weight ( 4 × 105, using proteins as standards). With this method, the range of molecular weights appears to be rather narrow. If “polymeric acids” are transferred from sodium carbonate, pH 10, into distilled water, selfassociation occurs and all species elute in the void volume. The weight-average molecular weight determined in 0.10 M sodium carbonate, pH 10, by the light scattering method is 1.7 × 105. Sedimentation velocity analysis at 20°C with the analytical ultracentrifuge gives a value for S20,w of 5.4 and the shape of the Schlieren patterns suggest a polydisperse sample with a relatively narrow range of sizes. Analysis of the molecular weight distribution by a sedimentation equilibrium method indicates that the range of molecular weights is 8 × 104 to 2.1 × 105. The partial specific volume (
) of “polymeric acids” is 0.874 ml/g. Viscosity measurements yield a value for η] of 2.5 ml/g, which indicates that the “polymeric acids” are compact (spherical or ellipsoidal) in shape. |
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