By Alex on Thursday, February 27, 2003 - 05:34 am:
I am looking for any references (www preferred yet not essential) on the influence of stationary phase pore size on chromatographic properties, especially for small molecules.
Influence on "column dewetting" is described. Is there any impact on selectivity?
Alexander Buske
By A.Nonymous on Thursday, February 27, 2003 - 09:12 am:
Here are some links, but its not much.
Link1
Link2
Good luck
By Uwe Neue on Thursday, February 27, 2003 - 03:19 pm:
I don't understand the question about selectivity changes after dewetting. If the packing dewets, it's no good anymore and needs to be rewetted.
By A.Nonymous on Friday, February 28, 2003 - 07:44 am:
If pore size is high enough, its possible to rewet, in other cases you never get the same selectivity. But if I understood the question its not the question about selectivity changes after dewetting, I thought it was selectivity changes in function of pore size.
By Alex on Monday, March 3, 2003 - 12:05 am:
I should ask more precisely:
Question: Can I expect seletivity changes (on small molecules) when using columns with different pore sizes (same type of modification, e.g. C18 with endcapping)? Does it make sense in method development to screen columns with different pore sizes in addition to screening of different bondings (C18 w/wo endcapping, polar endcapped columns, polar embedded columns, .....)?
Annotation: Influence of pore size on column dewetting is described: Material with smaller pore size tend to dewet more easy.
By Andreas Neumaier on Monday, March 3, 2003 - 06:10 am:
Dear Alex,
when using columns of the same type but different pore size you will see different seperations.
The wider the pore size the lesser the surface area. Decreassing surface area results in lesser retention.
It is possible to enhance the seperation of small molecules with wider pore size through increased %water - if the molecules in question could be seperated better in mobile phases with higher amounts of water.
Also is the retention of unpolar molecules on columns with wider pore size decreased. When trying to seperate a mixture of molecules with a wide range of polarity a column with wider pore size could show better results in shorter time.
Greetings, Andreas
By Uwe Neue on Monday, March 3, 2003 - 05:23 pm:
Often, the selectivity is different as well, not only the retention. There are a multitude of reasons for this.