Interaction studies of vinychloride with liquid foods by gas chromatography

Abstract

SummaryThe interaction of vinylchloride (VC) with liquid foods, such as water, olive oil and honey, was studied using the relatively new technique of Reversed-Flow Gas Chromatography (RFGC). The RFGC method permits the calculation of the VC diffusion coefficient in the liquid phase (water, oil and honey) and the determination of the partition coefficient of VC between the liquid and the carrier gas, as well as the determination of the Henry's constant of VC in the liquid food. From the variation of the above parameters with temperature, thermodynamic parameters (free and excess free energies, enthalpies, entropies and activity coefficients) were calculated for the adsorption of VC by liquid foods. These are discussed in comparison with the same parameters calculated from empirical equations or determined experimentally by other techniques.

Conversions of carbon monoxide oxidation over Pt−Rh alloy catalysts calculated by a new gas chromatographic technique

“…The experimental set-up of the RFGC technique for the kinetic study of the CO oxidation reaction over Pt-Rh alloy catalysts, which has been described in detail elsewhere [9,10,25] and in the Introductory section, is shown schematically in Figures 1 and 2.…”

“…The reversed-flow technique is a flow perturbation gas chromatographic method used for various physicochemical measurements [5][6][7][8][9][10] among which: the kinetics of surface-catalyzed reactions, in the whole range of conversions [11][12][13], the determination of adsorption equilibrium constants [14], activity coefficients [15], diffusion coefficients in binary and ternary mixtures [16][17], mass transfer and partition coefficients across gas-liquid and gas-solid interphases [18][19][20], interaction parameters of vinylchloride with liquid foods [9][10], deposition parameters of air pollutants on solid surfaces [21], interaction parameters in polymer-solvent systems [22], molecular diameters and critical volumes of gases [23], Lennard-Jones parameters [24], etc.…”

Reversed Flow Gas Chromatography: A Tool for Instantaneous Monitoring of the Concentrations of Reactants and Products in Heterogeneous Catalytic Processes

“…In this technique, instead of basing physicochemical measurements on retention volumes of elution peaks, their broadening and their shape distortion, due to physicochemical processes is under study. [14] It has been used to determine gas diffusion coefficients in binary and ternary mixtures, [15,16] Lenard-Jones parameters, [17] mass transfer coefficients on solids and liquids, [18][19][20][21][22] activity coefficients and solution thermodynamics, [23] adsorption equilibrium constants, [24] solubility and interaction parameters in polymer-solvent systems, [25] time distribution of adsorption energies, local monolayer capacities, local isotherms, and probability density functions for the adsorption energies on heterogeneous surfaces. This is analogous to relaxation techniques.…”

Development of new chromatographic methods for the study of exchange of pollutants between the atmosphere and the water environment

“…It has been shown before [82], that the height of the sample peaks produced by short flow reversals, when the vessel Lj of the diffusion column is filled with stirred water, is given by an equation similar to Eq. ( 78), but with the auxiliary parameters N, Χ, Y and Ζ expressed by different relations [83]:…”

“…we can find: The height h of each sample peak above the ending baseline is proportional to the concentration c{l, t) of the solute (vinyl chloride) in the sampling column at χ = Γ and at time / [83,84]:…”