zlignc
第5楼2014/09/06
If you are performing reversed-phase HPLC (C18 column):
1. The peak at 1.1 min is not likely from analyte (drug) because the retention time is so much shorter than 2 min and the peak appeared in both channels.
2. There should not be too much change in retention time because the solvent you used to dissolve sample has the same or lower elution strength than your initial gradient, if your injection volume is not very large.
3. Theoretically, the retention time should be slightly longer by using 5% methanol instead of 40% acetonitrile to dissolve your sample because 5% methanol has much lower elution strength than 40% acetonitrile. In reality, however, the change in retention is minimal because several μL of solvent in sample is not going to affect the retention time.