DMSO is highly risky at best. At worst, it's a bad idea. Very non-volatile (high bp), and "sticky". Typical solvents for GC-MS are hexane and dichloromethane.
DMSO is not an issue if your analytes are heavy enough to separate from the DMSO peak. We routinely look for analytes in DMSO. You do need to get the injector port hotter than normal as it does not easily volatilize.
You can use DMSO in sample prepration but you have to set Injector temprature upto 220 C. Still DMSO is Sticky so it may give broad peak shape. It's more prefarable to take an alternate solvent to DMSO.