The solubility of anthracene was measured in binary and ternary co-solvent-water systems. The binary systems consisted of water and a completely miscible organic solvent (CMOS); while the ternary system incorporated a partially miscible organic solvent (PMOS) into the binary systems. The data were used to test the following model:(UNFORMATTED TABLE OR EQUATION FOLLOWS) log Sᵃ(c,p,w) = log Sᵃ(w) + f(c) σᵃ(c) + [(Sᴾ(w) 10 (f(c) σᴾ(c))/D(p)] σᵃ(p). (TABLE/EQUATION ENDS) The terms on the right of the equality sign are the aqueous solubility of anthracene, the solubility of anthracene in CMOS-water, and the solubility of anthracene due to the incorporation of the PMOS, respectively. This model predicts that the incorporation of a PMOS, as a solubilized solute, in CMOS-water mixtures can lead to an increase in the solubility of anthracene due to the cosolvency effect of the PMOS. The results indicate a good correlation between the observed vs. predicted increase in solubility. The deviations observed may be explained by the interactions between the solvent components.

Graduation date: 1995

Nitrogen-heterocyclic compounds are commonly found in gas waste and coal cleaning residue. Within this general compound class, quinoline is especially important because it has the potential to induce liver carcinoma and it also has a high solubility in water. The pH-solubility profile of quinoline was determined in citrate-phosphate buffer at different ionic strengths. The pKa was observed to change with ionic strength. The intrinsic solubility is always reported as a constant. However, in this study the intrinsic solubility was observed to vary with ionic strength. The solubility of quinoline is dependent on pH as well as the ionic strength. At pH values lower than the pKa (4.96), quinoline is in the protonated form (QH⁺), and enhanced solubility was observed. At pH values higher than the pKa, quinoline is in the neutral form (Q) which is the form that determines intrinsic solubility (So). So decreased with increasing ionic strength. This observation can be explained as a salting out effect. From the solubility data the apparent ionization constant, pKa, of quinoline was obtained for the different systems.

Protein solubility is a problem for many protein chemists including structural biologists and those developing protein pharmaceuticals. Knowledge of how intrinsic factors influence solubility is limited due to the difficulty in obtaining quantitative solubility measurements. Solubility measurements in buffer alone are difficult to reproduce, as gels or supersaturated solutions often form, making the determination of solubility values impossible for many proteins. Protein precipitants can be used to obtain comparative solubility measurements, and they fall into three broad classes: salts, long-chain polymers, and organic solvents. Our group has used a model protein, RNase Sa, to create 20 variants that differ by the residues at a single surface-exposed position. We have measured the protein solubility of these variants and have generated an amino acid solubility scale, in the context of a protein, measured in ammonium sulfate. Here, we present solubility scales for these variants using PEG-8000 and isopropanol as precipitants. We find that amino acids can be divided into three groups based on their contribution to protein solubility: those that increase protein solubility, those that decrease protein solubility, and those that show little change in protein solubility as compared to our wild-type protein which has a threonine at the variable position. Of the 20 variants used here, the aspartic acid, glutamic acid, and serine variants show the greatest increases in protein solubility. Based on our results, we propose a strategy for increasing protein solubility: substitute exposed hydrophobic, asparagine, glutamine, and threonine residues with aspartic acid, glutamic acid or serine. To test this hypothesis, we utilize this strategy on a low solubility variant of RNase Sa. Here, we compare the use of representatives from two classes of precipitants, ammonium sulfate and polyethylene glycol 8000, by measuring the solubility of seven proteins. We find that increased negative surface charge correlates strongly with increased protein solubility and may be due to strong binding of water by the acidic amino acids. We also find that the solubility results obtained in the two different precipitants closely agree with each other, suggesting that the two precipitants probe similar properties that are relevant to solubility in buffer alone.

Thesis (PH. D.)--University of Chicago, 1916. / "A Private edition distributed by the University of Chicago libraries." "Reprinted from the Journal of the American Chemical Society, vol. 38, no. 12, December, 1916." Includes bibliographical references.

Thesis (Ph. D.)--Johns Hopkins University, 1917. / Biography.

Thesis (Ph. D.)--Ohio state University, 1922. / Vita. Photograph of "Conductivity bridge and thermostat" mounted on verso of t.p.

Thesis (Ph. D.)--Columbia University, 1918. / Vita.

Thesis (Ph. D.)--University of Nebraska, 1930. / Bibliography: p. 24.

Thesis (Ph. D.)--Columbia University, 1927. / Bibliography: p. [50-52].