Chromatography Forum

For a long time I calculated the equilibration time using column volumes based on void volumes, but recenctly in new job I met that people use the column volume based in the geometrical dimensions of column, what causes a big diference in the time. I use a column volume of 2,0 ml (4,6x250) and they use 4,2 ml for same column.

In most papers of LCGC it seems that they use void volumes as column volumes, but IUPAC have some official definition on column volume based only in geometrical dimention.

Am I wrong or there is no consensus on this?


Fabiano

It depends on the context and the purpose.

For estimating dead time, what counts is the void volume.

If you are calculating ion exchange capacity, then what counts it the total volume (capacity is typically given in milliequivalents per milliliter of column volume).

Tom,

The purpose is just let the column equilibrate after change the mobile phase.
My doubt is: when people say to let the column equilibrate for 10 column volumes they mean to use the void volume, right?

Fabiano

Fabiano,

when people say to let the column equilibrate for 10 column volumes they mean to use the void volume, right?

You are correct.