Chromatography Forum

at 240oC, what is the appropriate desorption time for SPME in order to completely get rid of carry over.

I've never really investigated that but that's the inlet temperature that I normally use.

I generally do manual injections so I base how long I leave the fiber in the injector on the cycle time of the GC. I leave the fiber in for 15 minutes while I'm equilibrating my next sample. Then I'm sure it's clean for the next sample. Most of the time, 30 minute SPME time (headspace is my main game) is good enough for my purposes. My typical GC run time is about 35 minutes.

If I leave the fiber in the inlet for 15 minutes + 30 minute SPME sampling is about 2 minutes longer than the GC cycle time. This maximizes my throughput for the day.

For SPME I desorb the anaytes in the injector always 1 min at 260 on a carb/DVB/PDMS fiber then stick the fiber in either the needle heater or a different inlet for at least 10-20 min.

Thanks a lot!

For SPME I desorb the anaytes in the injector always 1 min at 260 on a carb/DVB/PDMS fiber then stick the fiber in either the needle heater or a different inlet for at least 10-20 min.