Chromatography Forum

There is a general understanding that efficiency is inversely proportional to particle diameter. However the van Deemter C term includes terms which have particle diameter squared. Does anyone know the fundamental origin of this N being inversely proportional to the particle diameter rather than particle diameter squared?

Uwe Neue derived this relation in some online forum by differentiating van Deemter and setting it equal to zero but it seems that N being inversely proportional to particle diameter is only valid at the van Deemter minimum. Do people agree with that?

Thanks.

In normal life I don’t use such equations but my spontaneous idea is, that N ~ 1/dP is only a simplification of the van Deemter equation for comparable conditions. For a roughly estimation the C-term and therefore the part with squared dP will be less important (especially for particles <= 5 µm and medium flow rate).

I would be glad to learn more about this topic

At the moment I'm not able to have a look in the Halasz Paper (Ultimate Limits...) but maybe this would be helpful.

Regards
Klaus