[CSM]

Hello I'm new to this forum and thought I'd see if anyone would be able to help me out with this assignment question I have. The question is as follows

We want to collect purified analyte. What volume do we need to collect for an analyte if the flow
rate is 1 ml/min., the number of theoretical plates for the analyte is 5000 and the dead time is 2
minutes.  Do the calculation using for analytes with k’ = 2 and 10.

So far I've calculates t_r for both k' = 2 & 10 using
k' = t_r - t_m / t_m

t_r1 = 6 min
t_r2 = 22 min

Should I assume that the mobile phase velocity ~ flow rate i.e. u = 1 cm/min. Is there another way to relate flow rate to MP velocity?
This would allow me to get the analyte velocity using
v = 1/(1+k') x u
when k' = 2 v = 1/3 (mL/min)
The question seems quite ambiguous without mention of what type of chromatography is being used, GC, LC etc. No indication of sample size. Rather irritating

Any help would be greatly appreciated.
Thanks

[MOTOBALL]

You need to calculate the peak width in minutes at the baseline; then Volume = peak width x flow rate

Use,                      N = 16 (t_R / W)²

where    N = plate number

             tR = retention time

             W = peak width at baseline.

[CSM]

Ah! That makes sense. Thanks for the help