•From previous
•equation à
•
•Can plug in    n = L/tR   &   µ = L/tM
•
•Rearrange                        tR – tM
•                             kA’ = -----------
•and get                                tM
•
•Now have kA’ in terms of something easily measured in chromatogram •Compares how long it takes a species to move through system compared to unretained species
•Relative because ratio, Numerator = Net Retention
                 1
 n = µ x ----------
              1 + kA’