Chromatography Forum

Hi Guys,

I am just thinking of thermally desorbing and then reconditioning the PDMS-coated stir bar (twisters) in the 4 mm glass liner in the GC inlet. What inlet conditions, I should use. So far, I used splitless mode (1.5 ml/min) and close the purge valve for 5 min and temperature is always kept at 300 C.

We don't have the budget to buy Grestel thermal desorber or tube conditioner. So, other question is that why we cannot recondition the twisters in the simple oven or in inert oven?

I will appreciate your comments and suggestions.

Thanks
Moseebat

Isn't easier to condition your twisters using your TDU or TDS with a high split? Maybe even without cryocooling and using a fast oven ramping?

What you are doing is maybe OK if you have always an inlet idle and not too many twisters.

Maybe give a look also to this post
viewtopic.php?t=11186&start=0&postdays= ... onditioner

You need different gas flows for desorption of sample and transfer to the column, and conditioning. The desorption needs to be be splitless so that all the sample ends up on the column, the conditioning needs to have a high gas flow rate to efficiently purge the carryover and siloxane breakdown.

If you heat stir bars in air in an ordinary GC oven they will deteriorate very rapidly - they have to be in an inert gas to stop the siloxanes oxidising or hydrolysing.

Peter