Diffusion and thermodynamic measurements by supercritical fluid chromatography

Abstract

Abstract. Applications of supercritical fluid chromatography (SFC) to physicochemical measurements are reviewed. Emphasis is laid on the determination of binary diffusion coefficients at infmite dilution of solutes in supercritical solvents, and on actual or potential applications of SFC to the measurements of thermodynamic quantities in dilute, binary, supercritical mixtures. Physicochemical measurements emerge as a specific application field of SFC with many links to transport phenomena and to molecular thermodynamics of fluid-phase equilibria. Key words: supercritical fluid chromatography, d i p i v i t y measurements, diDsioncoescients, thermodynamic measurements, dilute supercritical mixtures

Performance of polyethylenimine-coated particles in packed capillary column supercritical fluid chromatography

“…Solutes of different polarities showed different behavior in response to changing temperature. Figure 7 shows the dependence of capacity factor on temperature for normal hexadecane, aniline, N,N-dimethylaniline, a-phenylethylamine, and N,N-dimethyl-a-phenylethylamine at constant [16,17]. That is,…”

Fast Solvating Gas Chromatography of Environmentally Important Compounds Using Polymer-Encapsulated Silica Particles

“…Figure 2 shows the effect of temperature on the apparent retention factors of three solutes of different polarity. The slopes of ln k vs. 1/T can approximate the transfer enthalpies of solutes from the mobile phase to the stationary phase [33]. As illustrated in Figure 1, the transfer enthalpies of solutes increased in the order of n-dodecane, N,N-dimethylaniline, and aniline, according to increasing polarity.…”

“…Diol-bonded silica particles were prepared according to a modified, previously published method [29,33]. Dried silica particles (0.5 g) were transferred to a home-made reaction vessel contain- ing 10 mL of 5% GPTMS aqueous solution, and the pH of the reaction solution was neutralized by adding 0.1 M NaAc.…”

Determination of thermodynamic properties by supercritical fluid chromatography

“…Although much of the relevant work has been covered elsewhere, e.g., in the respective sections of comprehensive reviews of analytical SFC [1][2][3] or unified chromatography [4][5][6], the field probably deserves stand-alone, periodical accounts [7] including also some specific experimental features and auxiliary thermophysical properties needed to process the chromatographic retention data. The present survey is a sequel to a short account [8] that appeared in 1991, and it largely retains the overall structure of its predecessor, comprising three major sections on thermodynamic measurements, instrumental considerations, and sources of auxiliary thermophysical data and theoretical models, respectively. Most of the results covered here appeared after 1990 although references to earlier work have been included when necessary.…”