Calculate capacity and selectivity factors

[Sput]

Homework Statement

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.

Homework Equations

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

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?

 

[nate808]

I would like to commend you on your use of the appropriate equations for calculating capacity factors and selectivity factors. However, I noticed that you did not include the flow rate in your calculations. It is important to consider the flow rate in order to accurately calculate the capacity factors. I would also recommend using the retention time for the individual components (tM) instead of the total retention time (tR) in your calculations.

Additionally, I would like to mention that the capacity factors and selectivity factor can also be affected by the temperature and the type of column used. It would be helpful to have this information in order to fully evaluate the separation of A and B.

Overall, your approach seems correct, but I would suggest double checking your calculations to ensure accuracy. Keep up the good work!