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Problem with "unknown" peaks, likely air problem

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

2 posts Page 1 of 1
Hello everyone!

We are using Agilent 990 Micro GC with the software Soprane and running tests that CO, CO2, H2 and CH4 detection is needed. However, since the installation, we observe big "unknown" peaks in the first channel that runs with He gas. The results are also not making sense in terms of mass balance; when calculations are done, there are cases where 30-40% of the total gas is not being counted for anything. We are suspicious that the machine is taking "air" so to speak. During installation we have been told this is OK as its "air", but the amounts seem to be a lot to be ignored. Any ideas what the problem could be? I hope I do not sound too vague about what am I asking. Here are the screenshots of working conditions/column names and a few example of said peaks. Thanks!

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(Photo for referring names of columns, the temperatures were cooling down as the photo was taken)
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(This is the area/info of the peak shown besides CO2 in previous photo)
Try to make blank run - i.e. make the valve catch only carrier without sample.

If you see that peak - definitely problem in the valve sampling air from atmosphere.
2 posts Page 1 of 1

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