extra column band spreading

[jiangds06]

if peak volume is 7ml, tubing volume between detector and outlet of column is 70ml. then what would be the final peak volume without considering band spreading in UV cell?
is it square root of (7^2+70^2)=70.4ml?

[jiangds06]

Hi can anyone help?

if peak volume is 7ml, tubing volume between detector and outlet of column is 70ml. then what would be the final peak volume without considering band spreading in UV cell?
is it square root of (7^2+70^2)=70.4ml?

[tom jupille]

To a good first approximation, independent contributions to band broadening are indeed root-mean-square additive.

The catch is that the tubing volume is not necessarily the same thing as the band broadening contribution. The latter will also depend on things like the diameter of the tubing, whether is it "swept" or "unswept" volume, whether the tubing is straight or coiled, and on the viscosity of the solvent (all of which will affect the mixing of liquid in the tubing).

I don't know enough about fluid dynamics to cite the equations, but if you catch a tame chemical engineer and buy him/her lunch, you should be able to get a more accurate answer.