Efficiency with HPLC Teaching Assistant, an Excel simulation of high performance liquid chromatography.
Download the Excel file from SaplingPlus, macmillanlearning.com, or the link in reference 27,27. and open the file. You will see a menu page with Resolution at the top left. If not, click on the blue home button in the top left corner. Select Efficiency from the menu. Check that you have the default settings: Lcol=150 mm; L_col=150 mm; dcol=4.6 mm; d_col=4.6 mm; dp=5.0 μm;dp = 5.0 μm; and Flow rate=1.0 mL/min. Flow rate = 1.0 mL/min. The red line in the bottom chromatogram labeled t0 is time for an unretained compound, which we call tM.t_M.
a. Use the flow rate slide bar to determine what flow rate gives the highest plate number NN and lowest plate height H. H.
b. Increase the flow rate from the optimum in (a). What happens to plate number NN and plate height H?H? What broadening process causes this change? What happens to retention time as you increase flow rate?
c. Return to the optimum flow rate found in (a). Decrease the flow rate. What happens to plate number NN and plate height H?H? What broadening process causes this change? What happens to retention times as you decrease flow rate?
d. Why is the plate height HH not 00 at the optimum flow rate in.