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Homework Help: Calculate capacity and selectivity factors

  1. Jan 16, 2012 #1
    1. The problem statement, all variables and given/known data

    The figure below shows a portion of a GC chromatogram for a mixture of two aromatic compounds labelled A and B. The separation employed a 2.20 meter packed column under isothermal conditions (90 C) and a flow rate of 12 mL/min. The figure shows the chromatogram in the region between 1.00 and 2.00 minutes, with the chromatograms expected for the individual components being overlaid. Calculate the capacity factors for each peak and the selectivity factor for the separation of A and B.


    2. Relevant equations

    I've been using ... A = t R - tM / tM and A = B / A

    3. The attempt at a solution

    sample A = 1.5minutes sample B = 1.6minutes (which are tR)

    1.25 = tM

    so sample A = 1.5 - 1.25 / 1.25 = -1
    so sample B = 1.6 - 1.25 / 1.25 = -0.9

    selectivity factor (A = B / A) -0.9 / -1.0 = 0.1

    Is this correct?
  2. jcsd
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