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Shape of the chromatogram on the first injection of the day

Question asked by denislafrance on Sep 28, 2018
Latest reply on Oct 16, 2018 by james_jenkins

I'm running TOGA on 7890A (one switch valve) with headspace autosampler 7697A.  I want to understand why the first injection of the day has always a baseline issue and my first peak (CO2) does not totally clear from the switch valve.  The second injection of the day is always OK.  I did attach an example to illustrate what I'm trying to fix.  The 2 injections are gas-in-oïl standard of 10ppm.  The first vial injection shows some baseline issues with the first peaks and some interference with the switch valve, while the injection from the second vial is OK.  Samples were run using the same method and injections are about 15 minutes apart.