How does one determine column volume?

pi * square of column radius*column length

for a 4.6 mm x 150 mm column, you have

pi X (2.3)squared x 150 = 2,493 cubic mm

or 2.493 cubic cm

Do you want the volume of an empty column, or are you looking for the internal volume of a packed column (column "dead volume")?

And, if the latter, do you want an estimate or an accurate measurement?

The relationship given in the previous post is correct for an empty column.

If you want to estimate the internal volume of a packed column, you also need to know what fraction of the packing is liquid. For commercial reversed-phase columns, the best general estimate is about 0.6, but it can obviously vary quite a bit from one packing to another (+/- 15 % or so ?). This works out to:
Vm = 0.5 * dc^2 * L
where
Vm = packed column internal volume in mL
dc = column internal diameter in cm
L = column length in cm

If you want an *accurate* value of the internal volume, you need to measure the dead time of the system at a known flow rate. This is the elution time of an unretained component. There is at least one other thread here on the forum discussing techniques for that, but the consensus seemed to be that, for reversed-phase, injecting a solution of uracil dissolved in the mobile phase seems to work. The column internal volume is the retention time multiplied by the flow rate.

Hope this helps.

-- Tom Jupille / LC Resources Inc.