Chromatography Forum

Hi all,

I just wondered if anyone knows of a way to 'forcefully' name a peak in chemstation? I know that there are high / low RT columns in the calibration table but this isn't working as our peaks are drifting around a lot during the course of the run. As a result chemstation is naming some peaks wrongly causing problems with subsequent calculations in Chemstore. Anyone got any ideas?

Cheers,

JKB84

our peaks are drifting around a lot during the course of the run.

I think this is the problem you need to fix. If you are running gradient, allow more equilibration volume/time. If running buffer, is there enough buffer capacity? Small leak? Is your pressure constant in isocratic? Is there a column oven controlling temperature? Is the mobile phase degassed? Are you using a pre-mixed mobile phase and one component is evaporating preferentially, changing its composition over time? Stuff like that.

chemstation is naming some peaks wrongly causing problems with subsequent calculations in Chemstore.

I don't believe ChemStore does any calculations, just electronic archive of data for data integrity; fix the chromatography.

Can you clarify what you mean by drifting around?. If it is variable RT during a runs of similar products, then yes, as CPG says - fix the chromatography.

If you are running sequence of samples of fractions from a chromatography column, it's not unusual for some peaks to appear and grow, whilst neighbouring peaks shrink and disappear during the sequence. That can screw up peak identities.

In that case, the peak RT windows have to be closely specified, and you may have to select one, or more, retention time reference peak, or add internal standard.

As far as I'm aware, unless later versions have changed, Chemstore performed advanced reprocessing calculations, as well as statistics and trends.

Bruce Hamilton