I am currently trying to get the best resolution between 7 peptides, each related to the native peptide by 2-6 aa's. I need 3-5 minutes between peaks and have thus far not found a proper gradient or MP prep. I am using n-Prop/ACN/TFA with a 3µm C18 column. I would like to keep the run time down to under 70 minutes. Any suggestions?

Have you tried to use DryLab yet? If you can track the peaks for two different gradient runs and send the retention times, column dimensions, gradient times, and dwell volume, I will at least be able to tell you if it is possible using the column and solvents you have selected.

Is there a reason you need that much *time* difference between the peaks? What kind of resolution (ratio of separation time to peak width) are you getting now? I can think of a straightforward approach to increasing the time between peaks if peak width is not an issue, and I can also think of straightforward ways to improve resolution. Getting both may be doable, but is harder.


-- Tom Jupille / LC Resources

You could also try using ACD/LC Simulator. It will function much like DryLab, but it can be easier to track the peaks, since it uses LogD calculation to predict relative retention times, provided that you know the structures. In addition, it can use those predicted LogD values in optimization as well.

Mike McBrien

Advanced Chemistry Development