The Alternative Axis of a Chromatogram

An elution curve of a chromatogram can be expressed using parameters other than the volume now of mobile phase as the independent variable. Instead of using milliliters of mobile phase, solute concentration in the mobile phase can be plotted against, time, or distance travelled by the solute band along the column and proportionally the same chromatogram will be obtained. This is illustrated in figure (I) 

As the curves are describing the same chromatogram, by proportion, the ratio of the variance to the square of the retention, in the respective units in which the Independent variables are defined, will all be equal. 

from the Plate Theory it has been shown that, 

The ratio, ( ), the column length divided by the number of theoretical 

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