To definitively identify the presence of a peak in a chromatogram and to be able to estimate its size for quantitative purposes, the peak height must be at least 5 times the noise level. The detector sensitivity (the minimum detectable concentration) (X_D), is that concentration of solute that will give a signal equivalent to twice the noise level and, so, the concentration of solute at the limiting (k') value will be 2.5X_D.

Solute concentration at the peak maximum is approximately twice the average concentration. Thus, if a mass (m) is placed on the column and the peak width is  ,then,

or                                                 (78)

Now, the maximum sample volume (V_i) that can be placed on the column that would restrict the increase to less than 5% has been shown to be,