Nonsteady state gas chromatography.
Item
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Title
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Nonsteady state gas chromatography.
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Identifier
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AAI9009753
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identifier
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9009753
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Creator
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Landau, Isaac.
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Contributor
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Adviser: David C. Locke
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Date
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1989
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Language
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English
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Publisher
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City University of New York.
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Subject
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Chemistry, Analytical
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Abstract
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Nonsteady state gas chromatography is a novel GC technique in which a solvent relatively volatile at the column temperature is injected into a column packed only with solid support, and allowed to equilibrate and be slowly eluted out of the column. During elution of the solvent, small samples of solutes of volatility greater than the solvent (volatility is the product of vapor pressure and activity coefficient) are injected repetitively. Because the weight of the solvent decreases with time as it elutes, the retention time of a solute injected repetitively will decrease over the lifetime of the column. It is possible to show that the limiting (infinite dilution) activity coefficient of the solute, {dollar}\gamma\sbsp{lcub}2{rcub}{lcub}\infty{rcub}{dollar}, is simply related to the solvent and solute vapor pressures, p{dollar}\sbsp{lcub}1{rcub}{lcub}0{rcub}{dollar} and p{dollar}\sbsp{lcub}2{rcub}{lcub}0{rcub}{dollar}, respectively, the average flow rate, F, and to the change in retention volume, {dollar}\Delta{dollar}V{dollar}\sbsp{lcub}\rm R{rcub}{lcub}0{rcub}{dollar}, over a time interval {dollar}\Delta{dollar}t, by {dollar}\gamma\sbsp{lcub}2{rcub}{lcub}\infty{rcub}{dollar} = (p{dollar}\sbsp{lcub}1{rcub}{lcub}0{rcub}{dollar}/p{dollar}\sbsp{lcub}2{rcub}{lcub}0{rcub}{dollar}) / ({dollar}-{dollar}1/F({dollar}\Delta{dollar}V{dollar}\sbsp{lcub}\rm R{rcub}{lcub}0{rcub}{dollar}/{dollar}\Delta{dollar}t)).;The technique has been shown to give reliable limiting coefficients for a diversity of binary systems. Two different solid supports have been compared and the results are presented. The column dynamics and mechanism of solvent elution have been explored.;The process proves to be a fast, efficient method of determining limiting activity coefficients which are necessary for thermodynamic relations and are useful in water pollution control, toxicological studies, process engineering, and other diverse areas.
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Type
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dissertation
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Source
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PQT Legacy CUNY.xlsx
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degree
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Ph.D.
