UPLC System overpressure...Problem with system or column?

[atw9]

Dear Mrs. atw9 ,

things always go wrong when the supervisor is away . Anyway, you've got the right attitude seeing this as a challenge to enjoy. And, yes, practical experiences are always better, but a sound understanding of the underlying theory never hurts, and for HPLC method development it's inevitable. You've just made the practical experience that sub-2-micron particles will create LOTS of backpressure...

Concerning your transfer/optimization problem: What's the reason for turning to the 1.7µm column? What was wrong with the original method on 2.6µm? Are you supposed to increase the resolution? Then going to 1.7µm and remaining the column length is logical. Are you supposed to speed things up? Then a shorter column with 1.7µm would be the logical step.
BTW running that 4.6mm 2.6µm core-shell column at 0,7mL/min is like driving a Ferrari in second gear. You might actually increase efficiency by increasing the flow rate (and at the same time decrease run time)...

The original rough method (not developed by me) was good, but not great. Correct it is more to do with resolution. But basically I was given this column and hoping to optimize this method (in any way I can), and validate it. I know running at 0.7mL/min is low but there were reasons for it and I can't recall the exact reasons right now. The method wasn't developed by me so I don't know what the challenges were when it was being developed.

Anyway I've been able to solve this now by tweaking a few things including reducing flow rate. Still annoyed this problem didn't happen the first week I was using it when the supervisor was around!

[carls]

FYI - the optimum flow rate for a sub-2um core-shell sorbents in 2.1mm ID columns is >0.35mL/min. There's really no cost in terms of efficiency when increasing the flowrate above this but you pay a relatively large price when running below this value. I'd recommend running at least 0.3mL/min.