"Manual" PTV?

[Roxanne42]

Just out of the blue, has anyone ever tried emulating a PTV by gradually raising the temperature of the inlet as the run goes?

I would assume it wouldn't work very well but just wondered if anyone had given it a shot and if anything good had come out of it. Someone here has a problem with a compound degrading at high temperatures and we don't have PTV's.


Thanks,

Roxanne.

[Peter Apps]

Hi Roxanne

I've done this by the crude method of switching the inlet heater off before the run, and then switching it on after I injected. I was trying to get rid of solvent rather than solving a thermal lability problem, but it worked OK.

The problem with nearly all modern GCs is that they refuse to do anything unless all temperatures are at their set points, and all the hardware is signalling that it is OK.

An alternative approach is to set a low inlet temperature, and then cryotrap on the column to refocus the wide inlet bands that you get from gentle slow evaporation.

Good luck.

Peter