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Soil and Atm gas analysis - which detector for CO2?

Discussions about GC and other "gas phase" separation techniques.

3 posts Page 1 of 1
Ok little info on my current setup (if I've left some info out that would help, just let me know!)
GC: SRI 8610C GC
Current Detectors: RGD (not currently in use) and TCD
Column: Haysep DB
Carrier Gas: Argon
Injection: 10 port sampling valve
Typically analyzing for on TCD: H2, N2, O2, CH4, CO2, N2O (occassionally He and CO)

We are switching projects and looking into doing soil gas and possibly some atm analysis as well. Namely want to look at CO2, but CH4 and N2O would be nice too. With my current setup of the TCD and Argon carrier, between 0.1-0.2% CO2 is pretty much the lowest reliable amount I can get. So far that's ok on the soil gas, but I fear as we move into fall/winter levels in some sampling sites may drop <LOD, and it looks like there may be interest in some atm sampling as well which is only a couple hundred ppm. So I'm needing to cover CO2 from about 1ppm on the low end to 1000-2000ppm on the higher end.

It looks like we will likely add on a stand-alone chassis to add an additional detector (the RGD takes up a good bit of room in my current GC). My initial thought was to add a FID/methanizer, however with more reading I'm wondering if we should look into a HID? As I mentioned earlier, CH4 and N2O at lower values would be a plus if that makes a difference (they're both about 0.1-0.2% LOD as well on my TCD) but its not required - the CO2 detection is the primary goal.

I'll add in a couple tidbits of info, which may (more likely may not!) help. Budget wise we may be limited, and this may not happen at all (my supervisor's supervisor has to ok the $$$ and with budgets being what the are right now...) So the lower the expense the better (otherwise I'd probalby ask for 10k in upgrades for all the work we really want to do, or a new GC alltogether, lol) ~5k would probalby go over ok, more than that would be iffy. And significant changes to my current setup capabilities (i.e. anything that would result in loosing my current analytes - even if we're not interested in half of them!) may not go over well...

So with that, I welcome any suggestions, or pros/cons on the options for modifying my setup! Or are there questions I need to ask SRI before going through with this? This is yet another new area for me (and I still consider myself somewhat of a novice to GC in general), so help is greatly appreciated!
Properly designed and maintained a methanizer with hydrogen carrier is very useful, but with Argon carrier, why not use a Ionization detector?

Of course, He would not be detected (use a TCD with nitrogen) but other gases should be no problem.

best wishes,

Rod
LDetek has a good plasma emission detector for greenhouse gases like you are looking for. Please have a look at the application note :
http://www.ldetek.com/uploads/cgblog/id ... LD12-1.pdf

Feel free to contact me at dgagne@ldetek.com for more information.

Kind Regards

Dany
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