A question van Deemter term by a student

[Sandra7]

van Deemter theory: H=A+B/u+Cu

In open tubular GC, the A term would be negligible, right? Is that because in GC, there is no particles causing no eddy diffusion and hence small A term? I think the way I am thinking is correct. if not please correct me.

[krickos]

Hi

Sadly I suck at expressing myself sometimes correctly in theoretically discussions, but here we go.

First be careful with open tubular (OT), there are WCOT (Wall Coted OT, very common), SCOT (Support Coated OT) and PLOT (Porous Layer OT).

WCOT has as you stated no particles so no multi path peak broadning appears there. Will not comment on SCOT, but PLOT on the other hand has a porous layer coated on the walls.......

[Sandra7]

Hi

Sadly I suck at expressing myself sometimes correctly in theoretically discussions, but here we go.

First be careful with open tubular (OT), there are WCOT (Wall Coted OT, very common), SCOT (Support Coated OT) and PLOT (Porous Layer OT).

WCOT has as you stated no particles so no multi path peak broadning appears there. Will not comment on SCOT, but PLOT on the other hand has a porous layer coated on the walls.......

Thanks. In my reading the textbook - I am about to read "Rate Theory" section, I see the subtitle for WCOT GC columns. The book doesn't mention the other two you mentioned. Thanks a lot.

[Jake]

Basically, yes. But best to use the Golay equation for WCOT columns.