I am developing a HS-GC method for residual solvent(methylene chloride) in protein sample. So I have to validate the method. However I got several problems.

1) I had used DMSO to dissolve the protein sample, but methylene chloride was detected in blank solution(DMSO). So I could not lower the limit of detection.
2) Is it possible not to use dissolving solution? I have known that solid sample is available in HG-GC method, but I wonder how I could perform the recovery test not using any solution.

I would suspect lab contamination as the source of methylene chloride contamination of the blank. It is very difficult to prepare standards in a general purpose lab that do not show contamination from common solvents in the blank. Try making the blank in a different lab, preferably one in which methylene chloride is no used.

It is difficult to run a recovery test without using a solvent. DMSO is known to be a very good sink for extracting organic vapors from the air. Perhaps another solvent could be used.