Gas chromatographic study of complexing in the system hydrazoic acid-tributyl phosphate-nitric acid-uranyl nitrate.

Elution gas chromatography has been used to study complexing of hydrazoic acid with tributyl phosphate (TBP) in hexadecane solution in the presence of nitric acid and/or uranyl nitrate. The study covered the temperature range 298-338 K, with concentrations of either additive up to 0.41 mol dm(-3). The results for hydrazoic acid elution at infinite dilution establish (a) that stoichiometry of the TBP-HNO3 complex is 1:1 and (b) that both 2:1 and 1:1 TBP-UO2(NO3)2 complexes co-exist in the system, the latter increasing in amount as the temperature is raised. Both HNO3 and UO2(NO3)2 act simply to reduce the amount of TBP free to form the 1:1 TBP-HN3 complex. Stability constants for the equilibrium UO2(NO3)2 TBP+TBP4<-->UO2(NO3)2 x 2TBP are presented.

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. The concentration of the solute in the head-space is measured by gas chromatography. The observed distribution is supplemented by vapor pressure and molar volume data and can be used to calculate the solubility and the activity coefficient of the solute in the aqueous phase. The partition coefficient, activity coefficient, and solubility for 18 alkylbenzenes in aqueous 0.5 M NaCl at 25 °C were measured by this method.

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/n-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.

Switching valves for use in multi-column gas chromatography.

Two switching valves for use in multi-column and frontal gas chromatography are described. Constructional and operational details are given and examples of use are quoted.

A novel multi-column gas chromatographic system.

Constructional and operating details are given of a special valve permitting selection of any one of four columns for connection to the detection system of a gas chromatograph, all four columns being connected to the carrier gas stream. If the retention times permit it, the columns may be used simultaneously for chromatographic separations and switched in turn into series with the detector for determination of the eluted components.