problem with the sample peaks

[excalibur30]

Although I get the proper peaks for standards I couldnt get the suitable peak with the samples. I am trying the determine the resveratrol contents of the red-wines. I used SPE (c18 cartridges) technique in the sample preparation step.
Chromotographic conditions:
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 also send the photos of standard and wine-sample peaks. If you have suggestions I will be glad.

[ym3142]

how did you prepare the standard and the sample? were their composites very close to the mobile phase? if not, try so.

[Uwe Neue]

I would attribute such things that you see to a very dirty mobile phase. Are you recycling the mobile phase?

[grreddy]

It is looking that there is a problem with the mobile phase. have you injected the mobile phase or not and have you checked the individual components for inerfering. if so try with different diluents so that you will get good shape.

g.r.reddy.