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Symmetrical peaks, with sample size independent retention times, are obtained when alkanols are chromatographed in columns packed with alkane stationary phases coated on a deactivated solid obtained by coating Chromosorb W with Carbowax 20M, followed by thermal treatment in inert atmosphere and exhaustive extraction with methanol. Adsorption on the solid support/alkane interface is precluded by this deactivation method, but adsorption on the gas/alkane interface persists as a non-negligible contribution to solute retention. Retention volumes of ten alkanols with three to five carbon atoms were measured at five temperatures within the 30–50°C interval in columns containing between 2 and 12 wt.% of squalane or of n-octadecane on the deactivated support. Partition and adsorption coefficients were obtained from the dependence of retention volumes on wt.% of stationary phase. Alkanols infinite dilution activity coefficients were calculated from partition coefficients; it is demonstrated that important errors are introduced on neglecting adsorption contributions. An indirect proof of consistency between calculated adsorption and partition parameters is given by comparing results obtained with both stationary phases. It is furthermore demonstrated that non-combinatorial contributions to the activity coefficients are independent of the alkane solvent.

Infinite dilution activity coefficients for twenty-three hydrocarbons in tetra-n-amyltin (TAT) and in tetra-n-lauryltin (TLT) at several temperatures between 40 and 60°C were measured by gas liquid chromatography. The results, together with those obtained in an earlier paper in tetra-n-octyltin (TOT), are compared and discussed in terms of the equation of state theory of Flory and of the lattice fluid theory of Sanchez and Lacombe.

Gas liquid chromatography was employed to measure the activity coefficients of a group of hydrocarbons at infinite dilution in tri-n-octyltin chloride at 40, 45, 50, 55 and 60°C. The partial molar excess thermodynamic quantities are interpreted by means of the Flory-Patterson theory, and compared with the results obtained for the same group of solutes in tetra-n-octyltin as the solvent. The alkanes activity coefficients and excess enthalpies in both phases are linearly related. Enthalpyentropy compensation in both solvents is discussed.

A method to measure solvent evaporation rates under controlled conditions is described. Vapors generated within a thermostated glass cell are swept by a nitrogen current and periodically injected into a chromatographic column and detector by means of an automatic sampling valve. Solvents with evaporation rates equal to or lower than that of cyclohexane may be studied. As the evaporative cooling is negligible, the method offers a definite advantage over classical gravimetric techniques.

Several concentration scales may be used to express the solute concentration, both in the condensed and in the vapour phase. Each choice of concentration units gives rise to a set of thermodynamic properties: distribution coefficient, activity coefficient, free energy, enthalpy and entropy of solution. The definitions and relationships between the different forms of activity coefficient are first reviewed. The standard states to which the thermodynamic properties obtainable from chromatographic data are referred are then unambiguously identified. Finally, some consequences on the correlation of the retention behaviour of members of homologous series are discussed.

Les vitesses d'evaporation de films composes d'octane-squalane et de toluene-sulfolane sont mesurees a l'aide d'une methode chromatographique en phase gazeuse

The retention volumes of eighteen hydrocarbons representative of different families and of acetone, diisopropyl ether and three chloromethanes were measured at four temperatures within the range 12–22°C on columns containing five different percentages of propylene glycol (PG) as the stationary phase. The relative magnitudes of the adsorption on PG, on formamide and on four glycols are compared and discussed in terms of the thermodynamic properties of the bulk mixtures with hydrocarbons, From this comparison, PG is found to possess the weakest adsorption effects, and some of the solutes studied exhibit no adsorption within experimental error. The thermodynamic properties of solution in PG are calculated and compared to those in formamide and in the glycols. Recent extensions of the regular solutions model are inefficient for calculating infinite dilution activity coefficients, but yield a very acceptable correlation between heats of solution and solute solubility parameters.

The paper is a continuation of the study of the interfacial properties of water by gas chromatography. Adsorption characteristics at zero surface coverage of a large number of solutes at the gas-liquid interface of water are presented. In all cases of relatively nonpolar solutes, the differential heat of adsorption is found to be less than the heat of liquefaction, indicating the gas liquid interface of water as a low energy surface. For n-propyl ether the heat of adsorption is 4 kcal/mole higher than the heat of liquefaction, strongly suggesting hydrogen bond formation between the ethereal oxygen and the hydrogens from the water surface of the liquid. Also studied was the infinitely dilute solubility characteristics of several non-electrolytes in the thin layers of water coated on wide pore diameter adsorbents. From layer thickness of about 30 A up to 2000 A, the solubility remains constant. Finally some preliminary adsorption and 'sorption' isotherms, determined by gas chromatography, are presented. (Author)

The use of gas chromatography for the study of the adsorption of insoluble vapors on water surfaces is described. The method involves using water coated on a porous support as packing material and presaturation of the carrier gas with water to prevent bleeding from the column. For saturated hydrocarbons it is found that the mechanism of retention is adsorption at the gas-liquid interface, whereas for aromatic hydrocarbons a mixed mechanism of adsorption and solution occurs. Contrary to results in recent literature, the differential heats of adsorption for the insoluble vapors are found to be 1 to 1.5 kcal/mol smaller than the heats of liquefaction. Possible causes for the discrepancy are examined in detail. The question of bulk water in the pores is explored via the partition coefficients of aromatic hydrocarbons. The solubilities and heats of solution are found to be close to the literature values, indicating the possibility of bulk water under the conditions of these experiments. A discussion of the advantages and disadvantages of the gas chromatographic method relative to static methods is presented.

The gas chromatographic retention behavior of nineteen halogenated hydrocarbons and of seven saturated hydrocarbons was measured at four temperatures from 55 to 65°C in tri-n-octylphosphine oxide (TOPO) and at 60°C in squalane (SQ). Thermodynamic functions of solution in TOPO were computed from these data. Strongly negative deviations from the ideal behavior were interpreted in terms of halogenated hydrocarbon+TOPO association, and the equilibrium constants were calculated by reference to the inert solvent SQ. The larger equilibrium constants correspond to solutes with a definite proton donor capability. The substitution of Cl for Br, however, produces an increase in the association constants suggesting the existence of other interaction mechanisms. Complexing of halogenated hydrocarbons with TOPO is markedly greater than with ethers, thioethers or tertiary amines., Centro de Investigación y Desarrollo en Tecnología de Pinturas