Chromatography Forum

Hello every one,

I have a problem with the long retention time. I try to make analysis of resveratrol. The chromatographic conditions as below:

Column: ODS c18 (250x4.6mm id, 5 um)
Detector: UV (306 nm)
Loop vol: 20 mL
Temp: 25 degree centrigrad
Mobile phase: ACN/Water/Acetic Acid (24.9/75/0.1)
Flow rate: 1 mL/min.

I found the retention time as 14.3 min.

When I changed the mobile phase as (19.9/80/0.1), and increased the flow rate as 1.3 mL/min. I got the retention time as 9.3. But the peak isnt still sharp enough I need to decrease the retention time more but I couldnt. Please help.

Note: When I tried to decrease the ratio of the ACN to %15 I couldnt find any peak. I think the ratio of 20% is suitable for ACN for this analysis.

Increase %ACN and/or use a shorter version of the column (I'm assuming that there is just 1 peak of interest here...)

Yay...increasing ACN proportion, not decrease it.

oh yeah...make sure the strength of the solvent that is used to dissolve your sample is less than that of the mobile phase.

thank you for your suggestions