A Study of the Performance of Packed Gas Chromatography Columns.

Abstract

The work reported here is consistent with, but not conclusive proof for, the coupling theory of eddy diffusion. The proof of this theory would be greatly advanced if it were possible to show the actual variation of A with flow velocity. This would be enormously difficult using the ordinary gas chromatographic methods. Glueckauf (17) has shown this kind of variation in a liquid system but it is difficult to judge the reliability of his data. The fact that the classical eddy diffusion picture seems to work in chemical engineering studies, many in the proper range of Reynolds numbers, indicates that the predicted transistion with velocity occurs at some point. The authors are not familiar with any experimental work which is in significant disagreement with the coupling theory.

High Column Efficiency in Gas Liquid Chromatography at Inlet Pressures to 2500 p.s.i.

“…These curves should have universal characteristics for all kinds of chromatography: Dal Nogare and Chiu (1) showed the general importance of reduced plate height, H/d,. The reduced or "effective" velocity, v = dpv/D,, has a greater range here than in any previous gas chromatographic study by a factor of about thirty.…”

“…I n this case flow velocity v is the natural variable of flow. The two main equations (2) for effective plate height are the classical form (1) and the coupling form where v is the flow velocity (velocity of an inert peak), A , B, C, and CI are the plate height terms for eddy diffusion, longitudinal diffusion, gas phase nonequilibrium and liquid nonequilibrium. These and subsequent equations do not account for turbulent effects (6).…”

Use of Combination Columns in Gas Liquid Chromatography.

“…Equation 4 is valid when linear and independent behavior exists between the solutes and the liquid phases, and V.,I is a constant per unit column length. The retention time, t~~ or the adjusted retention time, t l R .…”

“…The contribution of the resistance to mass transfer in the liquid phase term, CI, may usually be considered negligible for solutes with large k values on columns containing less than 10% liquid load; hence these columns are primarily gas-phase controlled (4,8).…”

The Spreading of Air Peaks in Capillary and Packed Gas Chromatographic Columns.

“…C, is often comparable with Cl and in certain cases considerably greater. Dal Nogare and Chiu (4) for example have established that C is definitely nonzero for both weakly and strongly sorbed substances. For both types C L should theoretically be zero and C is therefore due entirely to slow processes in the gas phase.…”