Separation Efficiency Versus Column Length. An Experimental Study With Capillary Columns

Abstract

The columns of different length used for studying the relation between HETP and column Iength are supposed to exhibit identical characteristics per meter. In the laboratory this condition cannot be rigorously fulfilled. The best approximation probably consists in starting the work with a relatively long capillary column followed by running shorter parts obtained by progressive cutting of the original column. Based on this procedure a marked increase of HETP with increasing column Iength is observed.

Chromatographic peak capacity and the factors influencing it

“…Kwok et a!., ( 12) have shown theoretically that frequently the increase is not linear. This fact was confirmed experimentally by, among others, Halasz (13) and Grob (14) who found that the HETP value of a gas chromatographic column increased with column length. In the experiments done by Grob (14), the increase in HETP was not as rapid as the increase in column length so that the overall plate number increased.…”

“…This fact was confirmed experimentally by, among others, Halasz (13) and Grob (14) who found that the HETP value of a gas chromatographic column increased with column length. In the experiments done by Grob (14), the increase in HETP was not as rapid as the increase in column length so that the overall plate number increased. Halasz (13, 15) maintains that the aforementioned decrease in efficiency is velocity dependent, becoming worse at a higher flow rate.…”

Versatile short capillary column in gas chromatography

“…The calculations were based on equivalent w-HETP curves for both long and short columns (S). In a more recent paper, however, Grob and Grob indicated that the efficiency of a capillary column per unit length increases with a decrease in length (9).…”