[diana80]

I got an impurity from my formulation. Filtered it out.. You could actually see something form after time. Now I need to dissolve it of course in something that can be run by HPLC. It dissolves in only dichloromethane. But dichloromethane is not a good choice because we don´t have that kind of HPLC equipment here. So CH2Cl2 would dissolve the tubings etc.
It seems like dichloromethane is the only solvent that dissolves this impurity. A good system would be 5% MeOH in CH2Cl2 ( I checked it by TLC) but it is so sad that I can not use it in the HPLC.

I have tried hexane, diethylether, Acetonitrile, Isopropanol, methanol and different mixture of hexane/acetonitrile and hexane/isopropanol and in the beginning also H2O/Acetonitile or H2O/Acetonitrile/MeOH.

I don´t really know the structure of the impurity, but I know it's a big molecule. around 835 m/z from mass spectrofotometry. I have a clue about the structure though: from NMR. It is not totaly non-polar.

Is there anything similar to CH2Cl2 that might dissolve this.. but not halogenated because I have to find a HPLC method to use. Some system? I will try THF next week, I don´t have it yet.. but I have my guessings that it will not work.

I actually tried to inject the sample dissolved dichloromethane in the HPLC but I used another mobile phase.. and nothing came out..I guess it just precipitated on the column.

What can I do?
Does anyone have a clue