GC syringe sampling: sub-ambient pressure

[www_ups]

hi all,
I am trying to sample the headspace gases in a reactor maintained at pressures below 1 atm (~200 Torr). I am using a septum adapter for syringe sampling. Can anyone guide me as to how this can best done ?
Thanks

[AICMM]

This will be an interesting challenge. I've never done it but I will ask some compatriots. First thing you need to look at is getting a mini-nert syringe valve (I think Valco has these) so that you can close off the syringe once you sample. This should prevent air incursion into the syringe between sampling and injection. Second thing I would ask is if you have exact pressure in the reactor since you will have to compensate values for pressure changes. Third, are you using a sample valve or an injection port injection?

Best regards.

[www_ups]

AICMM,
Thanks for the reply. I have a mini-inert syringe. I hope to withdraw ~100-250 uL each time from the ~20-25 ml reactor. I might have to consider pressure changes, but I do not think that it will affect the conversion a lot. I am injecting samples manually by withdrawing samples from a rubber septum.
Thanks