[salim]

I have a problem in the purification of a plant extract of polar compounds.
I get all like mountain in the beginning of the chromatogram using ACN / water as a mobile phase with diferente column.
some chemist can help me please?

[mehc]

What is the nature of columns you are using?

It seems that column is not showing selective adsorption of your polar compounds.

You should try by changing the ratio of water: acetonitrile in the mobile phase.

[salim]

I am using a Zorbax RX-C8 with a gradient of 5-100 ACN/water during 40 min, I have also change the ACN with Metanol but using a isocratic. think you very much

[mehc]

try by reducing the concentration of sample injected.

[salim]

I had injecting only 20 ul of the extract. do you think thas using DMSO to solubilise the extract is a problem?

[mehc]

I had injecting only 20 ul of the extract.

I wanted to say, reduce the concentration of your extract. Suppose the concentration of sample (from which you are injecting 20ul) is 10 mg/ml i.e. 10 mg of your extract in 1 ml of solvent. Reduce its concentration to 5mg/ml.

do you think thas using DMSO to solubilise the extract is a problem?

If possible,  dissolve your extract in the mobile phase solvents you are using.
Try by replacing DMSO with any suitable solvent, if mobile phase solvents not working in solubilising.