Theoretical and Experimental Study on the Use of Gas Chromatography in Turbulent Flow Conditions

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Abstract
It is relatively easy to carry out gas chromatographic analysis under conditions where the carrier gas flow is turbulent if open tube columns are used. This speeds up the mass transfer in the mobile gas phase. Conditions necessary to reach the turbulent flow region are given and equipment ia described. It is shown theoretically that in the fully turbulent flow of gas the retention times of all compounds should be independent of inlet pressure and of the carrier gas flow rate to the extent that the partition coefficients are themselves pressure independent, and the carrier gas ideal. Also, the HETP should be constant for all compounds, and for inert peak equal to about 5 times the column radius. Experimental data fully support these theoretical results. When the flow velocity is larger than the critical Reynolds number, the retention time decreases only slightly with increasing column inlet pressure, and the HETP decreases smoothly towards a limiting value equal to about 6r 0. The efficiency for retained peaks is, however, much smaller due to the effects of resistance to mass transfer in the liquid phase, and the analytical results are not as good as expected.