Calculate the selectivity factor, a (to one decimal places) between the two analyte peaks in the chromatogram: tr2 TR1 to = 1.2 min. tri = 3.1 min. tR2 = 5.8 min. Inject Chromatographic Terms Derived quantities Relative Retention (Selectivity factor) a = tz Iti = kx / k, = K /K, - Ratio of the adjusted retention times for two analytes. - Analyte 2 is always the more strongly retained species, i.e. tz >ti Therefore a > 1 - Describes the ability of a column to resolve (separate) two analytes. t2 tri' un CH Octane Unknown Nonane Injection time Time 20