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Question asked by cberdugo on Feb 27, 2018
Latest reply on Mar 14, 2018 by cberdugo

Hi all,

I am using a GC 6890 with split/splitless inlet to analyse reaction products. However, a problem has recently happened when the GC is running.


I have noticed the appearance of spikes in the baseline of the FID detector. The spikes appear occasionally. (See pictures below). The pictures attached correspond to the same experiment. As you can see the spikes occur before or even at the retention times where the analytes elute (between 13 and 15 min).


Spike in chromatogram5.png

Spike in chromatogram3.png

Spike in chromatogram2.png

Spike in chromatogram 6.png

Spike in chromatogram 7.png


I also noticed, that when I turned of the FID, the signal reading is not 0, but a value around 0.76 and keeps oscillating,



Closer look to the signal when FID is off:


Aside from this (and maybe related to) the peaks are eluting 1-1.5 minutes earlier for the FID.


Any suggestions on what to look at?