Chromatography Forum

Hi could anyone possibly help me with this problem?

A chromatographic column 4.0 metres long is known to have the following Van Deemter coefficients; A = 0.12 cm, B = 0.34 cm2s-1, C = 4.1 x 10-2s. It is operated at a flow rate of 3 cm s-1. Three peaks emerge when a hydrocarbon sample is injected;

Component Retention time / s peak height / cm

1 350 4
2 470 8
3 540 1

(a) Calculate the column parameters, peak widths and resolutions between each pair of peaks

I have calculated H to be 0.3563 making N=1122, and tr/w=8.38.
I now need to calculate the resolutions between each pair of peaks?

can anyone explain to me how to do this

cheers mark

Resolution is center-to-center separation divided by average peak width.

You have already calculated the relationship between peak width and retention time, so:

1. Calculate the widths of the two peaks of interest
2. Average them
3. Subtract the retention time of the first peak from the retention time of the second peak
4. Divide 3. by 2.