I am trying to determine residual solvents in mPEG-propionaldehyde. I am currently using a DB-624 column with an Agilent 7890A GC and G1888 headspace. I am looking for mostly class II (methanol, toluene, methylene chloride)solvents and then some class III. (ethyl acetate, tert-methylbutyl ether).

I tried using DMSO as the dissolution solvent, but had extra peaks due to reactions with the mPEG-propionaldehyde.

I also have used DMF, but I keep finding an odd peak (even with different brands) that may be due to ineractions although I am not sure what they would be.

I am wondering what would be the best solvent to try now. Anyone have some good ideas?