Posted by anne on Friday, October 14, 2011 at 6:30pm.


Hi, I have a question on HPLC (high performance liquid chromatography).
The procedure says to use a
4.6 x 150mm x 3um column.
The relative retention time of Impurity B with reference to the main peak is about 0.5min.
If I use a 4.6 x 100mm x 2.7um column, will the relative retention time of Impurity B with reference to the main peak still be about 0.5min?

1 answer

If I remember, flow rate is proportional to Radius4 /length

So here, your radius has been decreased by (2.7/3)=.9 or .9^4
Length has been shortend by (100/150+.666

so time is inversley proportional to the reciprocal of flow rate, or new time is .5min(.666/.9^4)=.5*1.01609 min

check this.

http://en.wikipedia.org/wiki/Hagen-Poiseuille_equation#Poiseuille.27s_equation_for_compressible_fluids