Sandra Teresita Martín del Campo

What type of LC separation are you planning to perform on the extract?

Why do you want to get rid of the water, given that the compounds you extracted are best soluble in aqueous conditions?

Eef Dirksen Thanks for the interest. As for the extracts, it was required that to pass the extracts through the LC-MS system (not sure about the technical details of the system), they should not be in an aqueous phase; they should be in methanol. I am trying to do a full scan of the extracts. Please let me know if there is a better way to do this latter.

This is also a question about which column you use. Often a C18 reverse phase column is used. You could well apply a water extract with 5 or 10% methanol (or acetonitrile) to such a column (provided that you have used MS grade water/methanol/acetonitrile). But expect that there will be loads of compounds in the extract.

if the concentration in the extract is low I would lyophilize it and resuspend it in eluent A.

If the concentration is high, use it as it is, but be aware, that precipitation might occur due to changes in the eluent composition. Perhaps test it ahead of LC-MS.

overall both appaches:

That might help to avoid clogging of the column. Perhaps short ultrasonic support might be necessary in the case of re-suspending after lyophilization.

In addition filter the final extract before injection

Yes the plant-based aqueous extracts can be injected in LC-MS and LC-MS/MS for identification of the phytochemicals present in it. Before injecting the samples make sure to solubilize it and filter it through a syringe filter.

Stefan Wittke Thanks for the answer. In fact, it's an ultrasound-assisted extract, also filtered. Would it be a good choice to lyophilize and resuspend in eluent A? Also, the concentration is low (1 g/L or less), and the concentration of molecules is fairly low according to colorimetric measurements. Please let me know if this is feasible.