Chromatography Forum

Dear All,
I propose to dissolve my water insoluble samples in DMSO for subsequent residual solvent analysis by SPME GC-MS.
I have not used DMSO before. Is there anything I should bear in mind prior to using it? How does it handle? I guess by definition its not volatile... From initial searches I know that I need headspace grade.
I intend to use incubation temperature of 80degC and typical GC settings of:
5 type column helium 1mlmin 50:1 split temperature ramp from 50 to 180 at 5degC/min.
Thanks in advance.
WK

Hi WK

Got limited experiance with SPME for residual solvents. Some general things about DMSO though.

You will get some DMSO in the HS, how much that actually goes on column depends on split, HS oven tempewrature and SPME fiber. With traditional static HS you get a decent DMSO peakt at HS oven at 80°C and split 1:5-10.

HS grade ? Given the split you use a normal 99,9% may do, so far (split 1:5-10) we so far have not needed to use a HS grade (more expensive). I suggest you buy the normal one first and see if it fits your purpose.

DMSO has a bp of about 189°C so just make sure you get all out of the fiber.

Column choice, well type 5 may do, depends on solvents, default ones in pharmacopieas is -624 or WAX type.

Beware that the DMSO will partition strongly into the fibre - its low vapour pressure is a disadvantage with SPME, and SPME suffers from competitive displacement of low concentration analytes by high concentration components.

Peter

WK,

Listen carefully to Peter.

Best regards,

AICMM

Hi All,
Thanks for the replies - I will post when I get chance to implement something.
Regards
WK