By Jeanette Norton on Wednesday, May 19, 2004 - 02:33 pm:
Typically we measure C2H2 by FID, N2O by ECD and CO2 by TCD. I have a GC6890 with room for two detectors, are there possibilities for measuring these three gases in headspace samples (often in the presence of acetylene) with two detectors?
By Jeanette Norton on Wednesday, May 19, 2004 - 04:37 pm:
Should be C2H4 needed to measure, sorry
By Anonymous on Thursday, May 20, 2004 - 08:39 am:
Jeanette,
I would think the choice would be concentration dependant also. Could you estimate the levels of these gases?
Regards,
Mark
By Jeanette Norton on Friday, May 21, 2004 - 01:45 pm:
Mark and others
Generally we are measuring in atmospheric ranges
for N20 0.5ppm up to 100
for CO2 200ppm -1% or so
for C2H4 1-1000 ppm
One issue is that some of the techniques use acetylene at 10% as a metabolic inhibitor or a alternative substrate.
The N2O does not need to be measured at the same time as the other gases (separate experiments)
By Gasman on Monday, May 24, 2004 - 09:23 am:
Jeanette,
You can measure the CO2 using a methanizer in conjunction with the FID. The CO2 is converted to methane which will burn in the FID. This way you will only need two detectors. The methanizer is normally built into the rear inlet position on the 6890.