Plate Theory and Extensions - Column Efficiency > Page 54


The peak width at the points of inflexion of the elution curve is twice the standard deviation of the Poisson or Gaussian curve and thus, from equation (47), the variance (the square of the standard deviation) will be equal to (n), the total number of plates in the column.

The variance of the band (sv2) in milliliters2 of mobile phase will be given by,

                                  s=  n(vm + Kvs)2




Thus, the variance of the peak is inversely proportional to the number of theoretical plates in the column. Thus, the greater (n), the narrower the peak, and the more efficiently has the column constrained peak dispersion.