peak resolution, Rs in chromatography

The separation of two peaks in terms of their average peak width at base ( $t R2 > t R1$ ):

$R s = t R2 − t R1 w b1 + w b2 2 = 2 ( t R2 − t R1 ) w b1 + w b2$

In the case of two adjacent peaks it may be assumed that $w b1 ≈ w b2$ , and thus, the width of the second peak may be substituted for the average value:

$R s ≈ t R2 − t R1 w b2$

Source:

PAC, 1993, 65, 819 (Nomenclature for chromatography (IUPAC Recommendations 1993)) on page 847

Orange Book, p. 108