Strange results from 6890N GC

Question

Hi all

We are using GC6890N in our lab to analyze dry gas, the GC with TCD and FID and four columns

Two weeks ago We noticed something strange in the results like a cycle.

N2 value it goes up and then goes back down.

Is there any advice to solve this problem?

Dheya

Admin · Accepted Answer

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krishna · Answer

Hi do one thing tight all connection properly and use IPA and water 50/50 ratio solution and check the leak again .with this solution .

Agilent · Answer

Hi Dheya, Since the CO2 area goes down (although only slightly) when N2 area goes up, I would suspect possibly a leak in the "sample-in" line. Testing with Snoop, water/IPA or a leak detector won't necessarily help because the sample in line is only pressurized while sampling. Also the gas sample is not necessarily detected by a leak detector. Try connecting He/H2 to the sample-in line and plug the sample-vent, then leak check all connections including the sample filter if used.

james_jenkins · Answer

Hi Dheya, In reference to the above, I would discourage the use of snoop as it has detergents and surfactants that can enter gas lines when they are leaking. This can raise the background of the instrument and cause unwanted side effects. I see that your leak detector is broken. The only other safe alternative is to use 50/50 MeOH and water. This will produce small bubbles and can help. The best would still be a leak detector. Regards James

Strange results from 6890N GC

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