Posted: Fri Aug 27, 2010 7:13 am
3 µl of a 0.2 mg/ml solution on a 4.6 x 100 mm column?
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Did the retention decrease from 23min at 80% MeOH to 3min at 60% MeOH?Yes there was a huge shift from 23-3min, I have changed injection volume up to 3 microlitres, there was no change.
Are you suggesting that I use pure water instead?
Yes the RT decreased from 23min at 80%MeOH to 3.9min at 60%meOH at both 1ml/min.Did the retention decrease from 23min at 80% MeOH to 3min at 60% MeOH?Yes there was a huge shift from 23-3min, I have changed injection volume up to 3 microlitres, there was no change.
Are you suggesting that I use pure water instead?
Why is the acetic added to the sample diluent (MeCN, 0.5% acetic acid)
This molecule appears to be neutral so buffer additives should not have much of an effect.
So the compound is weakly acidic (keto/enol tautomers?) and the retention behavior is very unusual. This retention behavior is more like HILIC than reversed phase which I would not expect for such a hydrophobic compound.Yes the RT decreased from 23min at 80%MeOH to 3.9min at 60%meOH at both 1ml/min.
I add 0.5%acetic acid to stabilize the rapamycin and right now i'm trying it without the acetic acid