Chromatography Forum

On the method, it was stated that the run time should be 30 minutes. But I noticed that my concerned analyte appears at 9 minutes. Can I cut my run time to make it only 15 minutes? Is there guidelines about that? Thanks

You should be able to alter run times. First, make sure that there are no other peaks eluting after your peak of interest. If there are later eluting peaks, you will need to extend your run time to encompass those peaks. If you cut your run time short and there are late eluting peaks, you run the risk of peaks wrapping around into your next injection.

Other wise, cutting your run time to 13-15 minutes would probably be a good option

If you are using isocratic conditions and there are no peaks after your peak of interest, you can shorten the run time.
If you are using a gradient, you can shorten the gradient but you need to be sure that there is sufficient equilibration time built into the gradient before the next injection. This only applies if it is not necessary to run the full gradient to clean off sample material from the run.

See above. Write your own test procedure to state "run time at least 12 minutes" or 15 minutes or whatever.

Provided we are talking isocratic elution, there are 2 important points to be considered:
1. Is the method a stability indicating one? And if so, you’ll need to run some degraded samples (could be expired product samples and/or force-degraded) and make sure you don’t see any peaks eluting later than the run time you’re planning to implement.
2. Inject a sample (preferably degraded) several times and watch out for potential ghost peaks in the consecutive injections (chromatograms) as well as the pressure.
The latter mentioned could be increasing with each consecutive injection and it would mean something stays on the column for longer time than your suggested run-time.

Best Regards