An Automated Coupled-Column Liquid Chromatography System for Measuring Aqueous Solubilities of Hydrophobic Solutes.

An automated apparatus is described for measuring the aqueous solubility of a sparingly soluble organic compound at many different temperatures. Water is pumped through a generator column packed with a chromatographic support coated with the organic compound, producing a saturated solution. The solute in a measured volume of this solution is extracted with an extractor column and analyzed by high performance liquid chromatography (HPLC).

A Head-Space Method for Measuring Activity Coefficients, Partition Coefficients, and Solubilities of Hydrocarbons in Saline Solutions.

An apparatus is described which measures the equilibrium distribution of a hydrocarbon between a gas and aqueous phase. Soluble hydrocarbons are extracted from an aqueous salt solution by very small bubbles of hydrogen generated electrolytically from a gold electrode located at the bottom of a cylindrical cell. The partition coefficient is determined from the volume of the aqueous solution and the solute concentration in the head-space after a measured volume of hydrogen has bubbled through the cell.

Measurements of the Octanol/Water Partition Coefficient by Chromatographic Methods.

A theoretical relationship is developed to provide a quantitative definition of hydrophobicity using established theoretical and semi-empirical relationships. A method of predicting partition coefficients of relatively water-insoluble third components between water and an immiscible second component is devised and tested. Comparison with experimental data for four classes of compounds in the water/-octanol system at 25 °C shows excellent agreement, indicating that values for substances for which direct determination is experimentally precluded can be calculated with confidence.

Calculation of Aqueous Solubility of Organic Compounds.

The aqueous solubility of 14 organic solutes has been calculated from their octanol/water partition coefficient and from their solute activity coefficient in octanol at infinite dilution. The solute activity coefficients were calculated from the Flory-Huggins and Hildebrand-Scatchard (FH-HS) equations and were found to be in good agreement with the activity coefficients determined from GC specific retention volume measurements. The calculated solubilities were in good agreement with the experimental solubilities.

Generator Columns and High Pressure Liquid Chromatography for Determining Aqueous Solubilities and Octanol-Water Partition Coefficients of Hydrophobic Substances.

Generator columns packed with a solid support and loaded with a liquid organic phase make it possible to rapidly and conveniently equilibrate water with the organic phase. By coupling the generator column to an extractor column for high pressure liquid chromatographic analysis of the aqueous solution, errors from surface adsorption and loss to the atmosphere are avoided. Using this method, the mean values and confidence limits at a 95 percent confidence level of the aqueous solubility, , and the octanol-water partition coefficient, , of n-propylbenzene at 25 °C were found to be = (4.

A Method of Measuring the Solubilities of Hydrocarbons in Aqueous Solutions.

An apparatus is described which measures the equilibrium distribution of a hydrocarbon between a gas phase and a liquid water phase. The method involves a multiple equilibration procedure which requires the analysis of only the gas phase. Gas-liquid chromatography was used for the hydrocarbon analysis because of its high sensitivity and selectivity.

Light Scattering Measurements on Solutions of Some Quaternary Ammonium Salts.

The general fluctuation theory for multicomponent systems has been applied in order to make corrections for the charge effect on systems of colloidal electrolytes where the gegenions and simple cations may have any valence. The basic equations of Prins and Hermans and Princen and Mysels were used for this derivation. The aggregation number and apparent charge were calculated from turbidity measurements on decyl-, dodecyl-, tetradecyl-, and hexadecyltrimethylammonium sulfate in different concentrations of NaSO, MgSO, and La(SO) solutions and on dodecyltrimethylammonium bromide in the KBr, CaBr, and LaBr solutions.