Principles and Practice of Chromatography - Factors Controlling Retention > Page 13

The peak height (h) is the distance between the peak maximum and the base line geometrically produced beneath the peak.

The peak width (w) is the distance between each side of a peak measure at 0.6065 of the peak height (ca 0.607h). The peak width measured at this height is equivalent to two standard deviations (2s) of the Gaussian curve and thus has significance when dealing with chromatography theory.

The peak width at half height (w0.5) is the distance between each side of a peak measured at half the peak height. The peak width measured at half height has no significance with respect to chromatography theory.

The peak width at the base (wB) is the distance between the intersections of the tangents drawn to the sides of the peak and the peak base geometrically produced. The peak width at the base is equivalent to four standard deviations (4s) of the Gaussian curve and thus also has significance when dealing with chromatography theory.

Factors Controlling Retention

The equation for the retention volume (Vr), as derived from the Plate theory (see ThePlate Theory and Extensions ) is as follows,

Vr = Vm + KVS