Scaling Up

[ChemicalBond007]

I am currently using this column.

My peaks are resolving very well, separated by 20 seconds. What I want to do is separate more material.

I want to use this column for the scale up. Note the same stationary material.


If I properly scale up the flow rate, sample concentration, and inject volume, do you think it will work?

Any suggestions will be appreciated.

[tom jupille]

It should.

The general approach is to do your loading study on the small column (keep increasing the mass on column until the separation gets as bad as you can live with). Then go to the bigger column.

Scale the flow rate to the cross-sectional areas of the columns.
Scale the injection volume and mass load to the volume of the columns.

[Mark Tracy]

Sure. Since the particle sizes are the same, it makes the math simpler. Scale the flow rate by (d2/d1)^2. Find the largest injection volume and sample concentration that you can stand on the smaller column, then scale the injection volume by (d2/d1)^2 * sqrt(L2/L1). You may be able to push the longer column a bit more on injection volume. The retention times will scale up by L2/L1. You may want to use a less sensitive wavelength for the UV detector. 0.010" capillaries should be OK. If the method is isocratic, you are finished. If it is a gradient, you have some more calculations to do.

[Uwe Neue]

I think that prep scaling is much simpler than most people think.

Rule #1: scale everything by the column volume: injection volume, flow rate, gradient volume (if you are running a gradient).

Rule #2: if you can’t do that due to limitations with your pump (either pressure or flow rate), work at the highest flow rate that your pump allows, but keep the scaling of the injection volume and the gradient volume. Since you will be working at a higher plate count, you may actually be able to inject a bit more, depending on how much you are overloading the analytical column.

[ChemicalBond007]

Thanks for all the help.

I have the data on the maximum load per injection. I will let you all know soon.