Behaviour of silica particles in sub-ambient temperature??

[rick1112]

Hi
I would like to know how silica particles will behave (in LC column ) when subjected to sub-ambient temperature (lets say 15or 10oC or even below that)…and how this affect the chromatographic performance, let say resolution, selectivity etc…
Thanks a lot

[danko]

The particles will behave roughly as they do at room temperature. If delta temperature is huge, there will be considerable particle size shrinkage. But I don’t think the effect will be too obvious.
When it comes to the mobile phase though, the changes in viscosity and solving power will be significant. And that would be the area that would need most attention, from chromatographic point of view.

Best Regards

[Uwe Neue]

As you decrease the temperature, peaks will be more retained and selectivity may change. Also, at a fixed flow rates, the plate-count will decrease and the pressure will increase. Otherwise, there is no problem.

[rick1112]

Hi
Thanks a lot for the reply…
Well one of my colleague recently told that in sub-ambient temperature there is shrinkage of silica particles (lets say ur working with 3 micron particle column..) which results in increase in resolution..(Although I disagreed with him…still need a confirmatory answer on the same)…so do you think this is possible??

[Uwe Neue]

I think your colleague is a joker...

If say a 3 micron particle shrinks to become a 2 micron particle, half of your column will be empty, and the particles will hang around in empty (or solvent filled) space, right?

[rick1112]

I think your colleague is a joker...

thats exactly what i thought when i heard it ...i even tried to argue with him..but he is kind of non listener...
but wht got me curious was i wanted to effect a subambient temperature have on silica and chromatography performance (have little idea about high temperature.. )

is there any specific application where a sub-ambient temperature is recommended or yields a good result??

[Uwe Neue]

Sub-ambient applications: sometimes, this could be the way to get the right selectivity, even if the peaks are wider.