splitting peaks with direct SPME

[doefus]

Hello,

I am using direct SPME for sampling, but sometimes the peaks in the beginning of the chromatogram split into two peaks. I am sure this concerns the same compound. I also had this problem once with thermal desorption of SBSE. Does somebody know what might be the problem??

In the same chromatogram where peaks were splitting, the peak area were much higher than in other samples (while it was the same concentration). Actually I really don't know what went wrong.

Thanks!

[AICMM]

doefus,

My first guess without a lot of information is that your phase is not thick enough for the analytes you want to handle. Try a thicker film column or a cooler starting temperature to re-focus your early eluters.

Best regards.

[Suresh Seethapathy]

Hello Doefus,

Could you tell us whats the analyte-SPME coating-GC inlet conditions-what liner you are using-flow rate. I have limited experience with SPME, but i am at University of Waterloo, home of SPME and i could ask around..

Regards,
Suresh.

[Bigbear]

Is this a new problem or has your method worked in the past? If you are just develping this method I would agree to lower your starting temp. We do blood volatiles via spme and cryo focus at -110C.