eslavko wrote:James_Ball wrote:
I was thinking nitrogen also as carrier since you don't seem to be looking for air gasses. I have seen a project for a home made nitrogen generator using the "pressure swing adsorption" method which will make highly pure nitrogen gas from compressed air. It will require some plumbing and switching valves but it is possible to make. You can probably find the plans online. The expensive part may be the molecular sieve used in the pressure cylinders to adsorb the oxygen from the air.
This seems like a lot of work and money too. As I don't know much about GC I just wish to know if separation of required gases is possible at all with diy GC. And for example I don't know how long 1kg bottle of balon helium can work so I don't know if that can pass price range. And what carierr gas is best for required sample. And I assume that I need to run carrier gas much before injecting sample to purge column.
Since Helium is normally separated from natural gas, I imagine balloon grade will have a lot of impurities of CH4 and O2 and possibly many other of the gasses you are looking for. You would need to place carbon and oxygen and probably moisture filters in the gas line to purify it before it goes into the GC.
Homemade GC are done all the time, there are a few threads here talking about it. Your sensitivity will depend some on the purity of your carrier. As long as your packing material is not sensitive to oxygenation then air could be used if you are not looking for any of its constituents. For air I would suggest an oil free compressor and place a carbon trap in the air to remove any traces of CH4 and CO2 that could be in the air.
A large cylinder of purified nitrogen would cost less than $200 and would last for several months in such a situation, or you can get the less pure nitrogen for less than $100 and use some purifier cartridges that will last several tanks and cut the overall cost a little more.
If you will be doing this over a long period of time you might want to look at a membrane nitrogen generator
https://nitrogen-generators.com/generat ... enerators/We use one of these that is just a small tube about a foot long that makes 99% nitrogen from compressed air and would probably be good for your needs.