Strange results from 6890N GC

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

Hi all

Many thanks for All responses.

Because coronavirus ,we cannot reach to the laboratory until April 12.After restrictions on movement are lifted we will update information about this problem.

Regards

Dheya

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.

Hi  

Many thanks for you reply

Now I cannot reach to our lab,I will do what you recommended after return to the lab.

Regards

Dheya

If you have not resolved your issue yet, there could potentially be a plug in the system as well. Plugs can play havoc with your injection pressures. The sample loops can get potentially plugged or the valve rotors can be plugged as well. Looking at your picture you can see black dust on the tops of each of your valve and that is caused by the rotor body starting to break down. If you get a chance to check on your GC, it might be worth your time to inspect the valves.

Hi dheyaaldeen,

I have marked this post as assumed answered due to its age, please feel free to update us with the result or post again if you are still having issues.

Regards

James