Chromatographic Study of Mixed Gas Adsorption by the Step and Pulse Method

Rybinski, Wolfgang von; Findenegg, Gerhard H.

doi:10.1002/bbpc.19790831123

Cited by 12 publications

(3 citation statements)

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“…Size exclusion chromatography (SEC) has been used extensively for the separation and characterization of polycyclic aromatic compounds (PAC) (1) especially in fossil-fuel-derived products such as petroleum asphaltenes (2) and coal-derived materials (3) in addition to its more common use for the characterization of polymers (4,5). The great utility of the method, at least in the case of common polymers, lies in the fact that for a particular column and mobile phase combination, the elution volume is related to molecular size or to some size-related parameter such as hydrodynamic volume, in a simple and straightforward manner (6,7).…”

Section: Resultsmentioning

confidence: 99%

“…The same type of phenomenon has been observed in GSC with an adsorbable component at subcritical conditions in the carrier gas. Several studies (1)(2)(3)(4)(5) have shown that the retention volumes of eluted solutes decrease significantly on graphitized carbon black adsorbents, when the adsorbable component in the carrier gas "coats" the solid surface with one-half of a monolayer or more. The so-called modifier inhibits the adsorption of the eluates, and the effect observed is exactly analogous to the observed decrease in retention when GCB is coated with a monolayer of nonvolatile stationary liquid phase (6)(7)(8).…”

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confidence: 99%

“…However, the use of volatile, rather than nonvolatile, modifiers provides the flexibility of pressure (flow) programming needed to vary the retention volumes and times continuously over a significant ranger Variations in retention volumes of different solutes with surface coverage by volatile modifiers do not follow a simple pattern, although there is usually a sharp drop in the retention volumes at high fractional surface coverage. However, cooperativity effects are often observed in which adsorption of the modifier increases the retention volume of some eluates (1)(2)(3)(4)(5)(6)(7)(8).…”

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Theoretical and experimental foundation for surface-coverage programming in gas-solid chromatography with an adsorbable carrier gas

Hung¹,

Parcher²,

Shores³

et al. 1988

Anal. Chem.

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Mass spectrometrlc tracer pulse chromatography was used to determine the adsorption Isotherms of benzene on a graphltlzed carbon black adsorbent at temperatures from 10 to 60 °C. Concurrently, the retention volumes of Infinite dilution samples of n -pentane, n-hexane, acetone, and 2-butanone were measured as a function of surface coverage of the adsorbent with benzene. The retention volume data Indicated that both cooperatlvlty and Interference effects controlled the adsorption and retention of molecular probes. The data at temperatures above 20 °C agreed with a retention volume equation previously derived from the two-dimensional scaled particle adsorption model. The data Interpretation yielded values for the Interaction energy between like or unlike species adsorbed In a two-dimensional condensed "phase". These values were In the range of 2.5 to 3.0 kcal/mol for pentane-, hexane-, and butanone-benzene Interactions, slightly lower, 1.5-2.0 kcal/mol, for acetone-benzene, and approximately 1 kcal/mol for benzene-benzene Interactions. Surface coverage programming was demonstrated to significantly reduce the retention times and Improve the peak shapes for a series of model solutes on GCB. The Investigation showed that chromatographic methods with diverse types of molecular probes can be used to Isolate and quantify the relatively weak, but Important, Interactions between adsorbates In a two-dimensional adsorbed phase.Gas-solid chromatography, GSC, is a well-established separation technique which has been especially useful for the analysis of mixtures of light gases. Yet the method is not as popular as many other chromatographic methods. The primary difficulties encountered in the practical application of GSC are (i) excessively long retention times, (ii) asymmetric elution peaks, and (iii) low chromatographic efficiency.Temperature and flow programming are established methods for diminishing the retention time and peak width of normally late-eluting solutes. Temperature programming is far more commonly used than flow programming in spite of the seeming advantages of flow programming, viz., low temperature, high speed, and simplicity. Unfortunately, there are several critical limitations of this procedure for GSC. The primary difficulty is the limited range of accessible flow rates. With inert carrier gases, the retention volume of any solute

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Section: Resultsmentioning

confidence: 99%

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confidence: 99%