No peaks found and restriction detected

I have started using GC-FID (Agilent 8890) since March for the first time. We are trying to measure the methane. I was trying to make a standard surve, so I injected 1000 ppm methane standard at first. Just to let you guys know no samples has been run so far on this machine. However, I am not getting any peaks for so long. We have tried the 99.5% methane, and we got very inconsistent peaks, and often I do not get any peaks. Recently, i got to know about Diagnosis test. i have run the test and It did not pass the "leak and restriction test" and "septum purge test". It shows," restriction detected in the primary flow path (inlet, column)". Is it the only reason we were not getting peaks? How would I resolve this issue? I am using GS-CarbonPLOT column and we inject through this white filter. I have attached the instrument setup and the column.

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  • Hello  ,

    I am not familiar with this configuration and not too familiar with valves. Maybe someone that is more familiar with either of these will be able to provide a more complete answer.

    But, generally a restriction in the flowpath may partially or fully prevent peaks from appearing on the chromatogram. If the flowpath is blocked, nothing will make it to the detector.

    I would trim the column ends (detector/inlet) and re-assess). From there, could be a restriction in the valve, or some form of a valve timing problem (valve being closed when it's supposed to be open). Could also be a restriction in the valve connections, or the inlet connections.

    If the septum purge is a problem then the problem might be the inlet EPC.

    What type of inlet are you using?

  • Hello,

    Can you inject with a small gas tight syringe directly into the inlet and see if you get a peak that way?  

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