The theoretical plate numbers for a gas chromatography system are found to 55.3, 96.9 and 89.8 for linear carrier gas velocities of 0.55, 1.65 and 3.10 cm\sec respectively. Calculate the maximum possible theoretical plate number for this system and the optimum carrier gas velocity to achieve it?
Here is one of many references for this: http://ion.chem.usu.edu/~sbialkow/Classes/361/GC/GC.html
You may need more than 3 points to fully form the curve for your system. Given the information provided, it should be fairly close to 1.65 cm/sec or maybe a little faster.
From the link, n=5.45(tr/W1/2)2
where n = # theoretical plates, tr = retention time, W1/2 = peak width at 1/2 the peak height.
You would run the column at several flow rated (linear velocities), measure the retention time and peak width at half-height, and plot n as a function of linear velocity.
I don't feel only 3 points is enough to plat that curve. I suppose one could try to solve for C and B with the data you have, see where a plot of C*v and B/v intersect, and that would be the optimal gas flow (see the link above for definitions of C and B). Adding those curves together would show the lowest HETP, which would let you determine n for that flow.
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