Peak capacity and resolution in capillary columns

Abstract

This series is intended to present the basic theory of chromatography in simple and clear mathematics which can be readily followed by the average chemist. The basic ideas are not necessarily novel but the approach and applications should be original and of interest to a large number of workers in chromatography rather than being limited to a small number of highly qualified chromatographers of great mathematical ability. Peak Capacity and Resolution in Capillary Columns A. S. SaidThe Kuwait Institute of Applied Technology, Kuwait.The simple peak capacity and resolution equations derived for the packed column do not apply so well to capillary columns. The reason is that in the course of their derivation the assumption was made that the peak width is proportional to the retention volume, measured from the point of injection. This is a satisfactory assumption in the case of a packed column but is not valid for capillary columns. Thus for a packed column (3)The only difference is that in the case of n, the subscripts 1 and 2 refer to any two points on the chromatogram and in the case of R they refer to the uncorrected retention volume, width and capacity ratio for the two neighboring peaks under consideration. As pointed out in reference[2], R may be defined as being the peak capacity between the maximum points of the two overlapping peaks.

Comparison of Empirical Peak Capacities for High-Efficiency Capillary Chromatographic Techniques

“…Effect of Linear Velocity on Peak Capacity . Several equations have been proposed for the calculation of peak capacity, ,− , and all show a dependence of peak capacity on both efficiency and t 1 . However, no systematic studies have been carried out on the effect of linear velocity on peak capacity.…”

“…Both efficiency and reduced plate height strictly refer to a single peak in the chromatogram. However, because chromatography almost always involves the separation of at least two compounds, peak capacity is a more useful − measurement to evaluate the overall separation potential of a chromatographic system.…”

Length‐time and capacity ratio optimization in chromatography

“…It was pointed out by Golay, Kaiser, and others including this author [6,8] where A" is a constant. Equation (24) does not lead to an optimum value for kp.…”

“…In the case of capillary columns, none of the above resolution equations applies. It was pointed out by Golay, Kaiser, and others including this author [6,8], that the relation between the number of theoretical plates N and peak width w is more appropriately expressed by the relation When the approximation w1 = w2 is not made such that each peak is taken with its own width we get Equation (24) does not lead to an optimum value for kp. It shows that the smaller is the value of k2 the smaller is the retention time when everything else including resolution is kept constant.…”

Aspects of High-Resolution Gas Chromatography as Applied to the Analysis of Hydrocarbon Fuels and Other Complex Organic Mixtures. Volume 1

“…Theoretical studies [176] of peak capacity and resolution have attempted to answer basic questions as to whether we are obtaining the full resolving power of our columns [177]. Also, further studies of the working range [178] of HRGC columns would seem desirable.…”