Hello, I analyzed my methanolic extract after evaporation in rotavap (only because I have to do others things before analysis),, but I think you can do it before. First, you have to filter with 0.45 syringe filter, or the indicated for the HPLC column. The most important thing that I consider, is not to plug the column (it is important to know the ratio of this part of the HPLC),