Chromatography Forum

I am currently working on a potency method transfer (reversed phase, isocratic system) and have been observing random retention time drifts of the peak of interest. This drift is not a gradual drift, but a sudden drift (most of the times exceeding 10%) in one random injection and then in the subsequent injection, the peak of interest would elute at the typical retention time.

Some important facts about this method: Use of a Zorbax column; 50% organic/50% buffer mobile phase; 80% organic/20% buffer sample and standard diluent; heated column temperature.

Has anyone observed this type of drift? This has been seen on multiple LCs, multiple columns, and different preparation schemes for both mobile phase and diluent.

I am highly interested in hearing feedback you may have to offer.

Thank you.

One possibility is occasionally sucking an air bubble in the pump. When the retention time of the peak of interest shifts, do other peaks shift as well?

Are you sure you are using the correct buffer for
the mobile phase/diluent ?

I notice that your mobile phase is 50% organic but your sample/standard dissolution solvent is 80% organic. If your injection volume is too large, this could result in a plug of 80% organic traveling through the column causing a shift in retention time. It is best to dissolve the sample and standards in a solution that does not exceed the organic concentration of the mobile phase.

Hello Jill,
Does your peak area vary with retention time?
J

Hi Jill,
Is your mobile phase mixed together? It happened to me 9 out of 10 when I used the mobile phase system 72:23:5 MeOH:H2O:THF for my analyses. The problem fixed after I mixed all reagents into one reservoir.