UHPLC/HPLC detectors

[RhysB]

Evening all,

My boss ahs asked a question of me that i hope someone can help with.

We are looking at buying a new HPLC/UHPLC and we were wondering the following.
With UHPLC you have lower flow rates and smaller flow cells. Will these small flow cells work under normal HPLC conditions.
(ie if we needed to run under lower pressures with normal HPLC columns are the detectors up to it).

And please don't shoot the messanger, I'm just passing the question on, as it was one I could not answer.

Cheers,
Rhys.

[Gerhard Kratz]

If you mean 1mm and 2mm ID columns it should be ok to use the UHPLC detectors. The small flow cell volume will give you sharper peaks.

[Hfranz]

It is no problem to use a small volume flow cell for conventional HPLC. Peak resolution should be even better, LOD might be worse because of more noise or a shorter light path.

[unmgvar]

with UHPLCs you have lower extra column volumes and dwell volumes when you use a 2-3 mm ID columns
so yes for those columns the use of what we called semi micro or micro size flow cell is preferable
for most vendors there is a UHPLC system that you can use with 3-4.6mm ID columns
but you must see the injection capabilities of the system. what is the maximum injection volume possible
in most cases UHPLCs systems are not made ready to use with 1mm ID columns, you need a nano-micro system for that.
make sure of several other things:
the column oven can work with 250or 300mm length columns.
if you have tertiary gradients then you need a LPG pump
the maximum possible injection volume of course
be ready to yes use the system with flows that are in the 1ml/min


remember that UHPLCs require much more maintenance, all samples and buffers need to be filtered 0.2u all the time, and even with standard columns it is very much preferable to still filter everything 0.2u. the tubing is very small in ID and clogs easily
and UHPLC will cost more to begin with, but you will be capable to save time and solvents and increase productivity that make it worth to use if you are ready to really use the instrument to it's full capabilities