Plate Theory and Extensions - The Peak Capacity of a Chromatographic Column > Page 98


Now, the effect of sample volume on peak width will be most significant for the early peaks (the most narrow peaks). In addition, the degrading effect of sample volume will progressively decrease as the capacity ratio of the peak becomes larger. Nevertheless, the resolution of both late and early peaks are equally important and, consequently, the limiting sample volume will be taken as that which restrains the dispersion of the first peak to 5% or less.


Thus, for an unretained peak,

Consequently, if the solute concentration in the sample is (Xi),


Equating equations (31) and (32),



Dividing both sides by (vm)noting that (), and simplifying,


and thus                          .                            (80)