Chromatography Forum

Hello everyone,

Our lab tries to analyse antioxidants via GC-FID.


The baseline is contaminated with some ominous peaks, which always retinate at the same time with different peak heights. They appear every one to three minutes over the duration of 20 Minutes
Sadly i can't find a way to upload a picture cause my host blocked all the possible image hosting sites. Therefore i am trying to show the chromatogram via dots

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So something like that, little peak in the beginning, followed by a bigger sligthly tailing dip retinating at the same time with different peak heights.

Could this be an issue of the detector?

Kind Regards and thanks in advance!

Leon

Advice on embedding pictures from moderator
https://www.chromforum.org/viewtopic.php?t=109934

Isopropane at normal conditions is gas, n-hexane is liquid. How do you inject sample - with gas loop?

What is the pure solvent chromatogram looks like?

Broken capillary column may show periodically appearing peaks.

Found a way to embed a Picture, hope that works:


this Picture shows a segment of the pure solvent measured 3 times.

Relating to the solvent: I meant Isopropanol/n Hexane (4:1) my bad

Found a way to embed a Picture, hope that works:


this Picture shows a segment of the pure solvent measured 3 times.

Relating to the solvent: I meant Isopropanol/n Hexane (4:1) my bad

When spikes period is equal to time required for carrier gas travel from head to output at specified flow rate, it means the column has a crack somewhere.

Or may be your H2 or Air delivery does not have buffer volumes to compensate compressor or H2 generator turning on/off.

Also you have nonpolar+polar solvent, which may capture water, which may exit as alteration in baseline (FID does not react on water, but water vapor impacts flame stability and baseline).
If you have highly-polar column like Wax, FFAP, you will see that water pseudo-peaks (as baseline pedestals)

Are you getting your gas from cylinders or generators?