Dear Stefano,

What are you trying to do and does it have to be polycarbonate?  I have
some other sources that may provide different MW  than you have tried.

There are many solvents to use but what problems do you have when you use
toluene or the other solvent you mentioned?

There are many different polymers to use also so this is why I question
you? I can possibly help.

Neal Christensen