Pressure limits of columns

[LCFan]

Hello,

when I ask chromatography specialists about the pressure limits of columns, I often hear two answers:

- the "classical" 5 micron columns have a limit of 300 - 400 bar
- the UHPLC columns (sub-2-micron) have limits of 900 - 1200 bar

I often use columns with particle sizes of 2.5, 3 and 3.5 microns.
Is there a rule of thumb in which pressure range they can be used? Up to 600 bar? Up to 800 bar?

Thank you very much for every hint.

Florian

[tom jupille]

For most silica-based packings*, the answer is "until the fittings start leaking".

That said, columns with particle sizes > 3 microns were generally designed to be used with "conventional" HPLC systems which have upper pressure limits around 400 bar in any case, and can typically maintain reasonable linear velocities at pressures considerably lower than that. So, unless you want to:
- use a *very* long column (500 - 1000 mm), or
- operate at an extremely high linear velocity, or
- you have a badly clogged column (in which case it's probably dead anyway),
there is no need for super high pressures.

The < 2 micron columns require a higher pressure to attain reasonable linear velocity, so they are designed for (and in fact require) instruments with 1000 bar or so of pressure capability.

* Most resin-based packings and some wide-pore silica packings are more fragile and may well have lower operating limits.